Obesity Diagnostics

Laboratory Tests and Ancillaries

Laboratory tests are done to detect, assess, and monitor comorbidities associated with obesity and identify the need for targeted interventions. This includes lipid profile (eg low-density lipoprotein cholesterol [LDL-C], HDL-C, and TG), fasting glucose level, HbA1c, thyroid function tests (eg thyroid stimulating hormone [TSH], free T4), uric acid, liver function tests (hepatic enzymes), renal function tests, and urine free cortisol levels (performed in patients with signs of Cushing’s syndrome). Notably, adiposopathic or atherogenic dyslipidemia includes elevated levels of TG, non-HDL-C, apolipoprotein B, LDL particle number and small dense LDL particles, and reduced level of HDL-C. Testing for natriuretic peptide may also be done; lower thresholds are used in obesity and exertional dyspnea to prevent heart failure from being underdiagnosed.

Tests to rule out polycystic ovarian syndrome (only if symptomatic; Rotterdam criteria may be used for screening polycystic ovarian syndrome in reproductive-aged women), electrocardiogram (ECG) if >50 years old or with risk factors (this may help in detecting atrial fibrillation in patients with obesity and heart failure), and polysomnography and other sleep studies in patients at risk for sleep apnea (eg suggestive signs and symptoms such as excessive daytime sleepiness, snoring, increased neck circumference or a high STOP-Bang [snoring, tiredness, observed apnea, high blood pressure, BMI of >35 kg/m², age >50 years, neck circumference >40 cm, male gender] score [≥3]) are also done. 

Imaging

Imaging modalities like chest X-ray (not routinely recommended), echocardiography (can detect left ventricular hypertrophy and pulmonary hypertension but may underestimate the degree of congestion in people with obesity and heart failure), and liver ultrasound (to screen for MASLD) may also be done.