Evaluation of unintentional weight loss

Used for broad assessment of intra-abdominal malignancy.

Guaiac can react with food or medicine leading to a false positive result, but quantitative fecal immunochemical tests (FITs) use antibodies specific to the globin part of human hemoglobin to detect small amounts of blood.[94]National Institute for Health and Care Excellence. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral in primary care. Aug 2023 [internet publication]. https://www.nice.org.uk/guidance/dg56 [108]Grobbee EJ, Wisse PHA, Schreuders EH, et al. Guaiac-based faecal occult blood tests versus faecal immunochemical tests for colorectal cancer screening in average-risk individuals. Cochrane Database Syst Rev. 2022 Jun 6;6(6):CD009276. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9169237 http://www.ncbi.nlm.nih.gov/pubmed/35665911?tool=bestpractice.com ​​​​​​ As globin degrades while traversing the gastrointestinal tract, theoretically these tests are less likely to detect globin from upper gastrointestinal bleeding.[108]Grobbee EJ, Wisse PHA, Schreuders EH, et al. Guaiac-based faecal occult blood tests versus faecal immunochemical tests for colorectal cancer screening in average-risk individuals. Cochrane Database Syst Rev. 2022 Jun 6;6(6):CD009276. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9169237 http://www.ncbi.nlm.nih.gov/pubmed/35665911?tool=bestpractice.com The US and UK guidelines report risk thresholds for testing among symptomatic populations.[93]National Institute for Health and Care Excellence. Suspected cancer: recognition and referral. Oct 2023 [internet publication]. https://www.nice.org.uk/guidance/ng12 [94]National Institute for Health and Care Excellence. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral in primary care. Aug 2023 [internet publication]. https://www.nice.org.uk/guidance/dg56 [95]Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on colorectal cancer. Am J Gastroenterol. 2017 Jul;112(7):1016-30. https://journals.lww.com/ajg/fulltext/2017/07000/colorectal_cancer_screening__recommendations_for.13.aspx http://www.ncbi.nlm.nih.gov/pubmed/28555630?tool=bestpractice.com [96]Patel SG, May FP, Anderson JC, et al. Updates on age to start and stop colorectal cancer screening: recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2022 Jan;162(1):285-99. https://www.gastrojournal.org/article/S0016-5085(21)03626-X/fulltext?referrer=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F http://www.ncbi.nlm.nih.gov/pubmed/34794816?tool=bestpractice.com ​​[109]Provenzale D, Ness RM, Llor X, et al. NCCN guidelines insights: colorectal cancer screening, version 2.2020. J Natl Compr Canc Netw. 2020 Oct 1;18(10):1312-20. https://jnccn.org/view/journals/jnccn/18/10/article-p1312.xml?ArticleBodyColorStyles=inline%20pdf http://www.ncbi.nlm.nih.gov/pubmed/33022639?tool=bestpractice.com ​​​​​​ The UK's National Institute for Health and Care Excellence (NICE) recommends certain quantitative fecal immunochemical tests for the recognition and referral of patients at risk of colorectal cancer.[93]National Institute for Health and Care Excellence. Suspected cancer: recognition and referral. Oct 2023 [internet publication]. https://www.nice.org.uk/guidance/ng12 [94]National Institute for Health and Care Excellence. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral in primary care. Aug 2023 [internet publication]. https://www.nice.org.uk/guidance/dg56 ​​​​​ Adults with a FIT result of at least 10 micrograms of hemoglobin per gram of feces should be referred using a suspected cancer pathway referral for colorectal cancer (for a diagnosis or ruling out of cancer within 28 days of the referral).[93]National Institute for Health and Care Excellence. Suspected cancer: recognition and referral. Oct 2023 [internet publication]. https://www.nice.org.uk/guidance/ng12 [94]National Institute for Health and Care Excellence. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral in primary care. Aug 2023 [internet publication]. https://www.nice.org.uk/guidance/dg56 ​​​​​​

Used for broad assessment of intra-abdominal malignancy.

Typically ordered if LFTs indicate possible obstruction.

Pancreatic protocol CT is more sensitive compared with CT abdomen/pelvis.

May be used as an adjunct to pancreatic protocol CT to detect small tumors and vein involvement.

Higher sensitivity for small tumors and better visualization of the mediastinum compared with chest x-ray.

Higher sensitivity for small tumors and better visualization of the mediastinum compared with chest x-ray.

Image the symptomatic region first (if identified). Can order if lymphoma is suspected and exam does not reveal lymphadenopathy.

Performed as part of staging.

Can be performed on peripheral blood, or preferably from lymph node suspension.

Image the symptomatic region first (if identified). Can order if lymphoma is suspected and exam does not reveal lymphadenopathy.

Goal of workup is to identify a lymph node accessible to biopsy.

Autoimmune hemolytic anemia may be seen.

Not ordered unless suspicion for multiple myeloma based on history, exam, or other lab findings.

Further staging involves additional imaging.

Indicated if lesion is easily accessible.

Further staging involves additional imaging.

Indicated when there is a strong suspicion of laryngeal cancer.

Order if mass found on exam, or if history is concerning for ovarian cancer; not ordered as a general screen for unintentional weight loss of unknown etiology. If a mass is found, it should be evaluated by a gynecologist/oncologist for staging and tissue diagnosis.

Consider if suspicious mass confirmed on imaging. Note that CA-125 levels can be elevated as a result of nonmalignant conditions.

Usually markedly elevated if presenting with unintentional weight loss.

Invasive procedure, but is often performed under local anesthetic and is well tolerated by most patients. May be performed as transrectal or transperineal procedure.

Diagnostic mammogram and/or ultrasound is recommended if clinically palpable mass. Screening mammogram if no palpable breast mass and presenting with unintended weight loss without an etiology found. Consider age of patient.

Indicated in patients with clinically positive axillary nodes and occult primary breast cancer or Paget disease of the nipple with breast primary not identified on mammography, ultrasound, or physical exam.

Total IgA is often routinely requested to assess for IgA deficiency, since the presence of IgA deficiency renders IgA-tTG insensitive.[110]Hill ID, Dirks MH, Liptak GS, et al. Guideline for the diagnosis and treatment of celiac disease in children: recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. J Pediatr Gastroenterol Nutr. 2005 Jan;40(1):1-19. https://journals.lww.com/jpgn/fulltext/2005/01000/guideline_for_the_diagnosis_and_treatment_of.1.aspx http://www.ncbi.nlm.nih.gov/pubmed/15625418?tool=bestpractice.com ​ IgA deficiency is more common in people with celiac disease than in the general population.[111]Kumar V, Jarzabek-Chorzelska M, Sulej J, et al. Celiac disease and immunoglobulin a deficiency: how effective are the serological methods of diagnosis? Clin Diagn Lab Immunol. 2002 Nov;9(6):1295-300. https://journals.asm.org/doi/10.1128/cdli.9.6.1295-1300.2002?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed http://www.ncbi.nlm.nih.gov/pubmed/12414763?tool=bestpractice.com ​ All diagnostic serologic testing should be done with patients on a gluten-containing diet.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com

IgA-tTG test is the preferred single test for detection of celiac disease, including in individuals ages <2 years who are not IgA deficient.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com ​ The test should be ordered in any case of suspected celiac disease. Higher titers have increased positive predictive value. All diagnostic serologic testing should be done with patients on a gluten-containing diet.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com

Small bowel histology is the most specific and sensitive test. If the suspicion of celiac disease is high, small bowel biopsy should be pursued even if serology tests are negative.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com

EMA is an alternative to IgA-tTG, with greater specificity but lower sensitivity.[113]Sheppard AL, Elwenspoek MMC, Scott LJ, et al. Systematic review with meta-analysis: the accuracy of serological tests to support the diagnosis of coeliac disease. Aliment Pharmacol Ther. 2022 Mar;55(5):514-27. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9305515 http://www.ncbi.nlm.nih.gov/pubmed/35043426?tool=bestpractice.com ​ A combination of high-level IgA-tTG (>10 times upper limit of normal) with a positive EMA in a second blood sample can be used to diagnose celiac disease in children. In symptomatic adults unwilling or unable to undergo upper gastrointestinal endoscopy, the same criteria may be considered as a diagnosis of likely celiac disease.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com All diagnostic serologic testing should be done with patients on a gluten-containing diet.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com

IgA-tTG and EMA-IgA may be less sensitive in children ages <2 years, therefore guidelines recommend that testing for celiac disease in children younger than 2 years include both IgA-tTG and DGP-IgG. Testing for celiac disease in children with IgA deficiency should be performed using IgG-based antibodies (DGP-IgG or IgG-tTG).[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com ​ All diagnostic serologic testing should be done with patients on a gluten-containing diet.[112]Chaudrey KH. ACG guideline: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):23. https://journals.lww.com/ajg/fulltext/2023/01000/acg_guideline__diagnosis_and_management_of_celiac.12.aspx http://www.ncbi.nlm.nih.gov/pubmed/36602833?tool=bestpractice.com

About 95% of celiac patients are positive for HLA-DQ2.[114]Sciurti M, Fornaroli F, Gaiani F, et al. Genetic susceptibilty and celiac disease: what role do HLA haplotypes play? Acta Biomed. 2018 Dec 17;89(9-s):17-21. https://www.mattioli1885journals.com/index.php/actabiomedica/article/view/7953 http://www.ncbi.nlm.nih.gov/pubmed/30561391?tool=bestpractice.com

Do not need to order to confirm diagnosis.

Nonspecific, but commonly abnormal.

Endoscopic evaluation - either colonoscopy, sigmoidoscopy, or upper GI endoscopy - should be performed depending on the suspected portion of the gastrointestinal tract involved.

Nonspecific, but commonly abnormal.

Order only if there is clinical suspicion for mesenteric ischemia, as stenoses may be asymptomatic.

Order only if there is clinical suspicion for mesenteric ischemia, as stenoses may be asymptomatic.

Order only if there is clinical suspicion for mesenteric ischemia, as stenoses may be asymptomatic.

Screening tools (e.g., patient health questionnaires) may be used. Positive screens should be followed by clinical assessment.

Screening tools (e.g., patient health questionnaires) may be used. Positive screens should be followed by clinical assessment.

Generally low due to decreased muscle mass. May be elevated if renal failure present.

Important to exclude thyroid disorders.

Recommended after 1 year of underweight in children and young people (earlier if they have recurrent bone pain or fractures) and after 2 years of underweight in adults (earlier if they have bone pain or recurrent fractures).[115]National Institute for Health and Care Excellence. Eating disorders: recognition and treatment. Dec 2020 [internet publication]. https://www.nice.org.uk/guidance/ng69 ​ 

Primarily a clinical diagnosis. Neuroimaging may be used for difficult cases.

The diagnosis of PD is made clinically, and in patients without atypical features, no additional diagnostic testing is indicated. If diagnostic testing is warranted due to atypical features or unclear clinical diagnosis, tests may include a dopaminergic agent trial.

Useful to confirm diagnosis.

Screening tests. Clinical judgment must be used to assign diagnosis of dementia. Neuropsychiatric testing can be used for uncertain cases.

May be useful as adjunct in the assessment of vascular dementia.

If the hypothalamic-pituitary-thyroid axis is functional, TSH alone is an adequate initial screening test. Usually ordered for most patients with unintentional weight loss even if not all classic symptoms are present

Evidence of unrecognized pulmonary TB or evidence of old healed TB (e.g., upper lobe fibrosis) may be present; such abnormalities should prompt sputum collection for smear, culture, and nucleic acid amplification testing.

Testing of 3 specimens (minimum 8 hours apart, including an early morning specimen) is recommended in many countries; consult local guidance.[116]Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines: diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan 15;64(2):111-5. https://academic.oup.com/cid/article/64/2/111/2811357?login=false http://www.ncbi.nlm.nih.gov/pubmed/28052967?tool=bestpractice.com ​​

Sputum specimen should be tested in patients with suspected extrapulmonary TB, as active pulmonary TB is seen in 15% to 20% of patients with extrapulmonary TB.[117]Geldmacher H, Taube C, Kroeger C, et al. Assessment of lymph node tuberculosis in Northern Germany: a clinical review. Chest. 2002 Apr;121(4):1177-82. http://www.ncbi.nlm.nih.gov/pubmed/11948050?tool=bestpractice.com [118]Weir MR, Thornton GF. Extrapulmonary tuberculosis. Experience of a community hospital and review of the literature. Am J Med. 1985 Oct;79(4):467-78. http://www.ncbi.nlm.nih.gov/pubmed/4050833?tool=bestpractice.com [119]Baydur A. The spectrum of extrapulmonary tuberculosis. West J Med. 1977 Apr;126(4):253-62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1237539/pdf/westjmed00272-0024.pdf http://www.ncbi.nlm.nih.gov/pubmed/855317?tool=bestpractice.com

Culture of Mycobacterium tuberculosis typically takes several weeks (up to 8), decisions on treatment are usually made before culture results are known.​​​​​

Microscopy should be performed on specimens collected from sites of suspected extrapulmonary TB.[116]Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines: diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan 15;64(2):111-5. https://academic.oup.com/cid/article/64/2/111/2811357?login=false http://www.ncbi.nlm.nih.gov/pubmed/28052967?tool=bestpractice.com [120]Nataraj G, Kurup S, Pandit A, et al. Correlation of fine needle aspiration cytology, smear and culture in tuberculous lymphadenitis: a prospective study. J Postgrad Med. 2002 Apr-Jun;48(2):113-6. https://www.jpgmonline.com/article.asp?issn=0022-3859;year=2002;volume=48;issue=2;spage=113;epage=6;aulast=Nataraj http://www.ncbi.nlm.nih.gov/pubmed/12215692?tool=bestpractice.com ​​

Culture result may take several weeks.

NAAT should be performed on at least one respiratory specimen (or specimen collected from sites of suspected extrapulmonary TB) when a diagnosis of pulmonary TB is being considered. NAAT may speed the diagnosis in smear-negative cases and may be helpful to differentiate nontuberculous mycobacteria when sputum is AFB smear positive but NAAT negative.[121]Centers for Disease Control and Prevention (CDC). Updated guidelines for the use of nucleic acid amplification tests in the diagnosis of tuberculosis. MMWR Morb Mortal Wkly Rep. 2009 Jan 16;58(1):7-10. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5801a3.htm http://www.ncbi.nlm.nih.gov/pubmed/19145221?tool=bestpractice.com Genotyping might be considered useful in outbreaks of TB to identify transmission of TB, especially when contact had not been appreciated in the course of epidemiologic investigations.

Although NAATs were originally designed and approved for respiratory specimens, they may also be requested on specimens from other sites where involvement of TB is suspected (e.g., cerebrospinal fluid, lymph node aspirate, lymph node biopsy, pleural fluid, peritoneal fluid, pericardial fluid, synovial fluid or urine).[116]Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines: diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan 15;64(2):111-5. https://academic.oup.com/cid/article/64/2/111/2811357?login=false http://www.ncbi.nlm.nih.gov/pubmed/28052967?tool=bestpractice.com [122]World Health Organization. WHO consolidated guidelines on tuberculosis: module 3: diagnosis: rapid diagnostics for tuberculosis detection. Mar 2024 [internet publication]. https://www.who.int/publications/i/item/9789240089488 ​​

In the US, use of NAATs for extrapulmonary specimens is not approved by the Food and Drug Administration, and use would be off-label. ​Several rapid NAATs are available for the diagnosis of TB, and some are also able to detect genes encoding resistance to TB drugs.[122]World Health Organization. WHO consolidated guidelines on tuberculosis: module 3: diagnosis: rapid diagnostics for tuberculosis detection. Mar 2024 [internet publication]. https://www.who.int/publications/i/item/9789240089488 ​​​​

Bronchoalveolar lavage may be indicated in patients in whom sputum induction is unsuccessful or in whom smear and NAAT are negative. Bronchoscopy is useful when other diagnoses are strongly considered or in patients in whom pulmonary TB is still suspected after other methods proved nondiagnostic.

Transbronchial lung biopsies are useful in the diagnosis of miliary disease as granulomas may be visible.

One Cochrane review found the lateral flow urine lipoarabinomannan (LF-LAM) assay to have a sensitivity of 42% in diagnosing TB in HIV-positive individuals with TB symptoms, and 35% in HIV-positive individuals not assessed for TB symptoms.[123]Bjerrum S, Schiller I, Dendukuri N, et al. Lateral flow urine lipoarabinomannan assay for detecting active tuberculosis in people living with HIV. Cochrane Database Syst Rev. 2019 Oct 21;10(10):CD011420. https://www.doi.org/10.1002/14651858.CD011420.pub3 http://www.ncbi.nlm.nih.gov/pubmed/31633805?tool=bestpractice.com [ ] What is the accuracy of lateral flow urine lipoarabinomannan (LF‐LAM) for detecting tuberculosis (TB) in symptomatic HIV‐positive adults?/cca.html?targetUrl=https://www.cochranelibrary.com/cca/doi/10.1002/cca.2824/fullShow me the answer [ ] What is the accuracy of lateral flow urine lipoarabinomannan (LF‐LAM) for detecting tuberculosis (TB) in unselected HIV‐positive adults (symptomatic or asymptomatic)?/cca.html?targetUrl=https://www.cochranelibrary.com/cca/doi/10.1002/cca.2825/fullShow me the answer​​​​​​ WHO recommends that LF-LAM can be used to assist in the diagnosis of active TB in HIV-positive adults, adolescents, and children with signs and symptoms of TB, or in those with advanced HIV or who are seriously ill.[122]World Health Organization. WHO consolidated guidelines on tuberculosis: module 3: diagnosis: rapid diagnostics for tuberculosis detection. Mar 2024 [internet publication]. https://www.who.int/publications/i/item/9789240089488 ​​

Culture would still be required for drug susceptibility testing (DST).

Bronchiectasis can be seen in chronic cases. Hemoptysis usually originates from bronchial arteries, but Rasmussen aneurysms from a pulmonary artery adjacent to a cavity can be the source of bleeding.

Residual bronchiectasis from old TB can cause hemoptysis.

Weigh the need for the medication against the potential effects of discontinuation and the likelihood that the medication is causing the weight loss. Medication can be discontinued if there is a high level of suspicion for causing weight loss and there are acceptable risks once the medication is discontinued. Further workup for other causes may be required.

Thresholds for sarcopenia are defined as appendicular skeletal muscle <20 kg for men and <15 kg for women; appendicular skeletal mass index <7.0 kg/m² for men and <5.5 kg/m² for women.[13]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019 Jan 1;48(1):16-31. https://academic.oup.com/ageing/article/48/1/16/5126243?login=false http://www.ncbi.nlm.nih.gov/pubmed/30312372?tool=bestpractice.com [124]Chen LK, Woo J, Assantachai P, et al. Asian Working Group for Sarcopenia: 2019 consensus update on sarcopenia diagnosis and treatment. J Am Med Dir Assoc. 2020 Mar;21(3):300-7.e2. http://www.ncbi.nlm.nih.gov/pubmed/32033882?tool=bestpractice.com ​​

DXA is the imaging technique recommended by the International Conference on Frailty and Sarcopenia Research to determine the level of lean body mass when diagnosing sarcopenia, due to its higher accessibility and lower cost and radiation exposure compared with CT and MRI.[125]Dent E, Morley JE, Cruz-Jentoft AJ, et al. International clinical practice guidelines for sarcopenia (ICFSR): screening, diagnosis and management. J Nutr Health Aging. 2018;22(10):1148-61. https://link.springer.com/article/10.1007/s12603-018-1139-9 http://www.ncbi.nlm.nih.gov/pubmed/30498820?tool=bestpractice.com ​ However, DXA cannot account for fatty infiltration of muscle, which can lead to an overestimation of lean mass.

CT is one of the recommended tests for estimating muscle volume and quality in patients identified clinically as having probable sarcopenia.[13]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019 Jan 1;48(1):16-31. https://academic.oup.com/ageing/article/48/1/16/5126243?login=false http://www.ncbi.nlm.nih.gov/pubmed/30312372?tool=bestpractice.com [125]Dent E, Morley JE, Cruz-Jentoft AJ, et al. International clinical practice guidelines for sarcopenia (ICFSR): screening, diagnosis and management. J Nutr Health Aging. 2018;22(10):1148-61. https://link.springer.com/article/10.1007/s12603-018-1139-9 http://www.ncbi.nlm.nih.gov/pubmed/30498820?tool=bestpractice.com ​ CT delivers high radiation levels.

MRI is one of the recommended tests for estimating muscle volume and quality in patients identified clinically as having probable sarcopenia.[13]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019 Jan 1;48(1):16-31. https://academic.oup.com/ageing/article/48/1/16/5126243?login=false http://www.ncbi.nlm.nih.gov/pubmed/30312372?tool=bestpractice.com [125]Dent E, Morley JE, Cruz-Jentoft AJ, et al. International clinical practice guidelines for sarcopenia (ICFSR): screening, diagnosis and management. J Nutr Health Aging. 2018;22(10):1148-61. https://link.springer.com/article/10.1007/s12603-018-1139-9 http://www.ncbi.nlm.nih.gov/pubmed/30498820?tool=bestpractice.com ​ MRI requires the absence of metallic implants or devices such as a pacemaker.

The Asian Working Group for Sarcopenia (AWGS) uses a bioimpedance cut-off for height-adjusted muscle mass of <7.0 kg/m² in men and <5.7 kg/m² in women.[124]Chen LK, Woo J, Assantachai P, et al. Asian Working Group for Sarcopenia: 2019 consensus update on sarcopenia diagnosis and treatment. J Am Med Dir Assoc. 2020 Mar;21(3):300-7.e2. http://www.ncbi.nlm.nih.gov/pubmed/32033882?tool=bestpractice.com

BIA measures the rate at which a painless low-voltage electrical current travels through the body. It is based on the principle that different tissues in the body allow the electrical current to travel at distinct speeds. Fat is more resistant than muscle or water, so the higher the resistance, the higher the body fat percentage. The equipment is widely available, portable, and affordable.[13]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019 Jan 1;48(1):16-31. https://academic.oup.com/ageing/article/48/1/16/5126243?login=false http://www.ncbi.nlm.nih.gov/pubmed/30312372?tool=bestpractice.com ​ However, it is less accurate than DXA.[125]Dent E, Morley JE, Cruz-Jentoft AJ, et al. International clinical practice guidelines for sarcopenia (ICFSR): screening, diagnosis and management. J Nutr Health Aging. 2018;22(10):1148-61. https://link.springer.com/article/10.1007/s12603-018-1139-9 http://www.ncbi.nlm.nih.gov/pubmed/30498820?tool=bestpractice.com

May follow with MRCP or ERCP, endoscopic ultrasound, MRI, or CT.[126]Vogel A, Bridgewater J, Edeline J, et al. Biliary tract cancer: ESMO clinical practice guideline for diagnosis, treatment and follow-up. Ann Oncol. 2023 Feb;34(2):127-40. https://www.annalsofoncology.org/article/S0923-7534(22)04699-3/fulltext http://www.ncbi.nlm.nih.gov/pubmed/36372281?tool=bestpractice.com ​ If high suspicion, can obtain MRCP as initial imaging test.

Not specific for cholangiocarcinoma.

Not specific for cholangiocarcinoma.

Elevated levels also seen in H pylori infection.

Reasonable to order in the presence of flushing and a negative workup for carcinoid tumor or multiple endocrine neoplasia. Pursue other causes of secretory diarrhea first as this is a rare condition.

May be better to detect rings compared with endoscopy; however, cannot perform biopsy without endoscopy.

Order only if high level of suspicion for SIBO.

If no cause of obstruction is found and retained food is present in the stomach after an overnight fast, this is supportive, but not confirmatory, of a diagnosis of gastroparesis.

Usually sufficient to make the diagnosis.

Should be ordered for suspected myelopathy.

With advances in neuroimaging, a patient with classic history, exam, and CNS imaging does not always require this.

May be helpful in combination with history and exam.

May also be helpful but is not by itself diagnostic.

There is no single test for cardiac cachexia.[12]Vest AR, Chan M, Deswal A, et al. Nutrition, obesity, and cachexia in patients with heart failure: a consensus statement from the Heart Failure Society of America Scientific Statements Committee. J Card Fail. 2019 May;25(5):380-400. http://www.ncbi.nlm.nih.gov/pubmed/30877038?tool=bestpractice.com ​ However, it is reasonable to recheck an echocardiogram, renal function, hematocrit, and thyroid function to assess for other potential causes of weight loss in a patient with heart failure. While inflammatory cytokines are elevated in cardiac cachexia, these are not routinely ordered.

Recommended if stroke affects swallowing function, or if choking or aspiration is witnessed.

A diagnosis of exclusion. PFTs are not diagnostic but are useful to restage disease. As smoking is a common risk factor for COPD and lung cancer, chest x-ray/CT should be considered.

PR3 antibodies are negative.

No specific tests; however, it is reasonable to check serum creatinine/BUN, electrolytes, CBC, and serum albumin.

High values (i.e., >15 micrograms/dL) make adrenal insufficiency unlikely. Values of 3-15 micrograms/dL are uncertain. If there is a high level of suspicion for the diagnosis, an ACTH stimulation test should be ordered.

A reasonable initial screen unless the morning cortisol is performed first.

Should be ordered only if there is clinical suspicion for pheochromocytoma because weight loss is an uncommon presentation of this rare disease. Positive test should be followed up with imaging.

Less convenient than serum test.

Pooled data from a meta-analysis of over 5000 RA patients give RF a test sensitivity of 62% and a test specificity of 87%.[127]Nishimura K, Sugiyama D, Kogata Y, et al. Meta-analysis: diagnostic accuracy of anti-cyclic citrullinated peptide antibody and rheumatoid factor for rheumatoid arthritis. Ann Intern Med. 2007 Jun 5;146(11):797-808. http://www.ncbi.nlm.nih.gov/pubmed/17548411?tool=bestpractice.com [128]Taylor P, Gartemann J, Hsieh J, et al. A systematic review of serum biomarkers anti-cyclic citrullinated peptide and rheumatoid factor as tests for rheumatoid arthritis. Autoimmune Dis. 2011;2011:815038. https://www.hindawi.com/journals/ad/2011/815038 http://www.ncbi.nlm.nih.gov/pubmed/21915375?tool=bestpractice.com

More specific for RA than rheumatoid factor. Multiple assays are available.

May be normal early in disease course.

Not diagnostic, normal values do not exclude diagnosis.

Not specific; order only if clinical suspicion of SLE.

may be indicated to support the diagnosis, depending on the presence of other clinical, laboratory, and imaging criteria.[129]Robson JC, Grayson PC, Ponte C, et al. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for granulomatosis with polyangiitis. Ann Rheum Dis. 2022 Mar;81(3):315-20. https://ard.bmj.com/content/81/3/315.long http://www.ncbi.nlm.nih.gov/pubmed/35110333?tool=bestpractice.com

A thorough workup for other causes should still be performed.

Recommended screening is anti-HIV 1 and 2 antibody, and p24 antigen. Very early cases may be detected by PCR testing, although these are unlikely to present with unintentional weight loss.

Very early cases may be detected, although these patients are unlikely to present with unintentional weight loss.

Obtain sample from symptomatic area diagnosis. Stains may be negative and culture may be slow growing.

Used clinically to confirm amebic intestinal infection.

ELISA or direct fluorescence antibody.

Usually not seen with routine test; request special evaluation.

Usually not seen with routine test; request special evaluation.

Usually not seen with routine test; request special evaluation.

Serology testing by ELISA.

Certain organisms may be more difficult to culture.[130]Talha KM, DeSimone DC, Sohail MR, et al. Pathogen influence on epidemiology, diagnostic evaluation and management of infective endocarditis. Heart. 2020 Dec;106(24):1878-82. http://www.ncbi.nlm.nih.gov/pubmed/32847941?tool=bestpractice.com

Owing to its rarity, consider only if all other workup for these symptoms is negative.

Excludes many clotting abnormalities as a cause of bleeding and bruising.