Differentials
Primary hypothyroidism
SIGNS / SYMPTOMS
Fatigue.
Attenuated growth.
Cold intolerance.
Constipation.
Declining school performance.
Dry skin.
Coarse hair.
Goitre.
INVESTIGATIONS
Free T4 will be low for age.
Thyroid-stimulating hormone (TSH, also known as thyrotropin) will be elevated for age.
Secondary hypothyroidism
SIGNS / SYMPTOMS
Fatigue.
Poor growth.
Cold intolerance.
Constipation.
Dry skin.
Coarse hair.
INVESTIGATIONS
Free T4 will be low for age.
Thyroid-stimulating hormone (TSH, also known as thyrotropin) will be low or normal for age.
Cushing syndrome
SIGNS / SYMPTOMS
Attenuated growth.
Violaceous striae.
Buffalo hump.
Central adiposity.
Moon facies.
Hirsutism.
Hypertension.
Diabetes.
INVESTIGATIONS
The 24-hour urinary free cortisol or midnight salivary cortisol is elevated for age.
Prader-Willi syndrome
SIGNS / SYMPTOMS
Short stature.
Small hands and feet.
Almond-shaped eyes.
Picking on skin.
Delayed puberty.
Developmental delay.
Hyperphagia.
History of poor feeding and hypotonia as infant.
INVESTIGATIONS
Genetic testing shows imprinting error on chromosome 15q11-q13.
Bardet-Biedl syndrome
SIGNS / SYMPTOMS
Dysmorphic extremities.
Retinitis pigmentosa.
Developmental delay.
Hypogonadism.
Renal defects.
INVESTIGATIONS
Mutations in several different genes have been linked to Bardet-Biedl syndrome.[77]
Pseudohypoparathyroidism
SIGNS / SYMPTOMS
Short stature.
Round face.
Short metacarpals.
Developmental delay.
Basal ganglia calcification.
INVESTIGATIONS
Serum calcium levels show hypocalcaemia.
Serum phosphate levels show hyperphosphataemia.
Serum parathyroid hormone level is elevated.
Monogenic obesity
SIGNS / SYMPTOMS
Severe, early-onset obesity.
Usually associated with disruption of normal appetite control mechanisms.
INVESTIGATIONS
Genetic testing identifies gene mutation in candidate genes such as leptin, ghrelin, adiponectin, peptide YY(3-36), and melanocortin 4 receptor (MC4-R).[3][78]
Mutations in MC4-R are the most common cause in children, occurring in approximately 5% of cases.[79]
The obesity gene map database and the National Institutes of Health and Centers for Disease Control and Prevention database of association studies can be used as a source of candidate genes: National Institute on Aging: genetic association database Opens in new window
Hypothalamic obesity
SIGNS / SYMPTOMS
Severe obesity following treatment for intracranial lesions such as craniopharyngioma.
Excessive appetite.
INVESTIGATIONS
Abnormal hypothalamopituitary testing.
Obesity due to medication
SIGNS / SYMPTOMS
Several classes of medication can be associated with weight gain, including neuropsychiatric medications, (eg, risperidone, olanzapine, clozapine)., anti-epileptics (eg, sodium valproate), insulin, corticosteroids, antibiotics, and acid-suppressing agents.[31][32][59]
INVESTIGATIONS
Discontinuation of drug as a therapeutic trial.
Lipoedema
SIGNS / SYMPTOMS
Lipoedema is a condition characterised by swelling and enlargement of the lower limbs due to abnormal deposition of subcutaneous fat often dismissed as simple obesity. In addition, easy bruising and pain with soft tissue pressure, as well as the step-off at the ankles are hallmark symptoms.[80] Disease onset is usually at or soon after puberty but can develop at other times of hormonal change (such as pregnancy or even menopause).[81]
INVESTIGATIONS
Lipoedema is diagnosed based on the symptoms and clinical examination. Imaging studies, such as CT and MRI may be useful in clinical examination. Patients with lipedema demonstrate diffuse fatty hypertrophy throughout the bilateral lower extremities without skin abnormalities on MRI and CT imaging. NIH: Genetic and Rare Diseases Information Center: Lipedema Opens in new window[82]
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