Tests
1st tests to order
CBC
Test
In the acute stage, a mild to moderate normochromic anemia is observed, along with an elevated white blood cell count with left shift.
During the subacute stage, thrombocytosis is often observed.
Result
anemia, leukocytosis, and thrombocytosis
erythrocyte sedimentation rate (ESR)
Test
During the acute stage, many acute phase reactant markers, such as ESR, CRP, and serum ferritin, are significantly elevated. ESR tends to return to normal levels at the end of the subacute phase toward the convalescent phase.[36]
Result
elevated, but should not be used to determine response; intravenous immune globulin (IVIG) has been shown to increase ESR levels
CRP
Test
During the acute stage, many acute phase reactant markers, such as erythrocyte sedimentation rate, CRP, and serum ferritin, are significantly elevated. CRP levels normalize quicker than other biomarkers. CRP is used to guide management decisions.
Result
elevated
echocardiogram
Test
Echocardiography is crucial in management of KD to identify coronary artery abnormalities. During the acute stage, a baseline echocardiogram is important to rule these out and seek evidence of myocarditis, valvulitis, or pericardial effusion. Diffuse dilation of coronary lumina can be observed in 50% of untreated patients by the tenth day of illness.
Perform echocardiography at diagnosis and routinely repeat it at 1-2 weeks and 4-6 weeks after treatment. If coronary artery abnormalities are significant (Z score >2.5) during the acute illness, perform echocardiography at least twice per week until luminal dimensions have stopped progressing.[1] It is important to detect coronary artery thrombosis because failure to prescribe timely thromboprophylaxis with the rapid expansion of aneurysms is a cause of morbidity and mortality.[1] Perform echocardiography for patients with expanding large or giant aneurysms twice per week while dimensions are expanding rapidly, at least once weekly in the first 45 days of illness, and then monthly until the third month after illness onset.[1]
Be aware that in the first week of illness the echocardiogram is typically normal and does not rule out the diagnosis.[1]
For children with suspected incomplete KD and fever, obtaining an echocardiogram with coronary artery measurements without delay is strongly recommended by the American College of Rheumatology.[37]
Result
signs of coronary abnormalities during acute stage: left anterior descending coronary artery or right coronary artery Z score ≥2.5; coronary artery aneurysm seen; three or more other suggestive features, including decreased left ventricular function, mitral regurgitation, pericardial effusion, or Z scores in left anterior descending coronary artery or right coronary artery of 2.0 to 2.5
Tests to consider
serum LFTs
Test
Icteric and anicteric hepatitis can develop, with mild elevations in aminotransferase values observed in 40% of patients.
Elevated alanine aminotransferase levels can indicate a more serious course.
Bilirubin levels are elevated in 10% of patients.
Result
elevated liver enzymes; low level of albumin
urinalysis
Test
Will show a mild to moderate sterile pyuria of urethral origin in 50% of patients.
If urinalysis is abnormal, a culture should be performed to rule out a urinary tract infection.
Result
sterile pyuria
chest x-ray
Test
Looks for cardiomegaly in the case of pericarditis, myocarditis, or subclinical pneumonitis.
Should be performed to assess baseline findings and to confirm any clinical suspicion of congestive heart failure.
Result
cardiomegaly or, more rarely, pneumonitis
electrocardiogram
Test
Needs to be obtained to evaluate for various conduction abnormalities. Children with KD may also have acute infarction.
Tachycardia, a prolonged PR interval, ST-T wave changes, and a decreased voltage of R waves may indicate myocarditis. Q-wave or ST-T-wave changes may indicate a myocardial infarction.
Result
conduction abnormalities and/or myocardial infarction
ultrasonography of the gallbladder
Test
May be necessary if liver or gallbladder dysfunction is suspected.
Result
hydrops of the gallbladder in some patients
ultrasonography of the testes
Test
In case of testicular involvement in males, a scrotal sonogram to evaluate for epididymitis should be performed. Epididymitis is an inflammatory process that can occur in various vasculitides and affects boys aged 9 to 14 years. It can be observed in younger boys with Henoch-Schonlein purpura and KD.
Result
epididymitis in males with testicular involvement
lumbar puncture
Test
May be needed in patients who present with high fever and nuchal rigidity.
Some patients with KD may have aseptic meningitis.
Aseptic meningitis could be one of the adverse effects of intravenous immune globulin treatment.
Result
aseptic meningitis in some patients
magnetic resonance angiography
Test
Free-breathing 3-dimensional coronary magnetic resonance angiography may accurately define coronary artery aneurysms in patients with KD. Cardiovascular magnetic resonance is useful for demonstrating coronary artery aneurysms and other coronary pathology.[38]
Result
coronary dilations or aneurysms
cardiac catheterization and angiography
Test
A subset of patients with KD, especially those with findings of large or giant coronary artery aneurysms (>8 mm in diameter), may require cardiac catheterization and angiography to further characterize these abnormalities, although care should be taken when considering invasive arteriography in the presence of ongoing systemic inflammation since complication rates (such as catheter-related myocardial infarction) may be higher.
Result
coronary artery aneurysms
natriuretic peptide tests
Test
Elevated N-terminal pro-brain natriuretic peptide (NT-proBNP) may be present in KD.[34] However, these do not automatically confirm the diagnosis as they may be associated with a wide variety of cardiac and noncardiac causes.
Result
elevated levels of natriuretic peptides
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