From the Guidelines
Initial laboratory tests for patients presenting with weight gain should include thyroid function tests, fasting blood glucose or hemoglobin A1c, comprehensive metabolic panel, and lipid profile. These tests are essential for identifying potential endocrine causes of obesity and examining the various components of metabolic syndrome, as well as kidney function and blood liver enzymes 1.
Key Laboratory Tests
- Thyroid function tests (TSH, free T4) to assess for hypothyroidism, a common medical cause of weight gain
- Fasting blood glucose or hemoglobin A1c to evaluate for diabetes and impaired glucose tolerance
- Comprehensive metabolic panel to examine kidney function, electrolyte balance, and blood liver enzymes
- Lipid profile to assess for dyslipidemia, a key component of metabolic syndrome
Additional Tests
Additional tests may be ordered based on clinical presentation and suspected abnormalities, such as:
- Complete blood count to assess for anemia or other hematologic abnormalities
- Pregnancy testing for women of reproductive age
- 24-hour urinary free cortisol test or overnight dexamethasone suppression test if Cushing's syndrome is suspected
- Insulin levels to evaluate for insulin resistance
- Prolactin levels if medication-induced weight gain is suspected
- Sex hormone levels if polycystic ovary syndrome is a consideration in women with irregular menstruation and hirsutism 1.
Considerations
It is crucial to prioritize these tests based on the patient's clinical presentation, medical history, and risk factors for complications associated with obesity, such as cardiovascular disease, type 2 diabetes, and certain types of cancer 1.
From the Research
Initial Laboratory Tests for Weight Gain
The following laboratory tests are recommended for patients presenting with weight gain:
- Overnight dexamethasone suppression test (ODST) to screen for Cushing's syndrome 2
- Comprehensive metabolic panel point-of-care test to reduce length of stay in the emergency department 3
- Endocrine testing, such as screening for hypothyroidism, may be recommended in certain cases 4
Specific Tests for Cushing's Syndrome
For patients suspected of having Cushing's syndrome, the following tests may be recommended:
- Midnight serum cortisol (MserC) levels 5
- Late-night salivary cortisol (LNSC) concentrations 5
- Dexamethasone-CRH (Dex-CRH) test 5
- 24-hour free urinary cortisol test 2, 5
Correlation between Insulin Clearance and Insulin Responsiveness
Insulin clearance and responsiveness may be correlated in patients with weight gain, particularly in those with Cushing's syndrome or other endocrine disorders 6
Recommendations for Endocrine Testing in Obesity
Endocrine testing is not recommended in the absence of clinical features of endocrine syndromes in obesity, with the exception of screening for hypothyroidism 4