Laboratory Workup for 26-Year-Old Female with Weight Gain and Difficulty Losing Weight
Order a comprehensive metabolic panel, fasting lipid profile (total cholesterol, LDL, HDL, triglycerides), thyroid function tests (TSH with reflex to free T4), hemoglobin A1c, and consider additional testing for polycystic ovary syndrome if menstrual irregularities or signs of androgen excess are present. 1, 2
Core Initial Laboratory Tests
The essential baseline workup should include:
Comprehensive metabolic panel (CMP): Screens for glucose abnormalities, liver dysfunction (particularly nonalcoholic fatty liver disease which is common with weight gain), kidney function, and electrolyte disturbances 1, 3, 2
Fasting lipid profile: Must include total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides to evaluate for dyslipidemia and cardiovascular risk factors 1, 3, 2
Thyroid function tests: TSH is essential to rule out hypothyroidism as a secondary cause of weight gain; if TSH is abnormal, reflex to free T4 and free T3 1, 3, 2
Hemoglobin A1c: Critical for screening abnormal glucose metabolism, prediabetes, and type 2 diabetes, which are increasingly common with obesity 1, 3, 2
Complete blood count (CBC): Evaluates for underlying conditions that may contribute to weight gain 2
Additional Testing Based on Clinical Presentation
For Menstrual Irregularities or Signs of Androgen Excess
At 26 years old, polycystic ovary syndrome (PCOS) is a critical consideration, as obesity exacerbates PCOS phenotype including metabolic dysfunction 4:
- Prolactin level: Check if menstrual irregularities or galactorrhea are present 5
- Total or free testosterone levels: Obtain if signs of androgen excess are noted (hirsutism, acne, male-pattern hair loss) 5
- FSH and LH: May be indicated for comprehensive evaluation of menstrual irregularities 1
For Suspected Cushing's Syndrome
If central obesity, "moon face," or violaceous striae are present:
Physical Examination Components to Guide Testing
Beyond standard vital signs, specifically assess:
- Waist circumference: Provides critical information about central adiposity and cardiovascular risk that BMI alone cannot capture; central obesity is an independent mortality risk factor 3
- Blood pressure: Essential for cardiovascular risk assessment 1
- Acanthosis nigricans: Suggests insulin resistance 3
- Hirsutism: Indicates possible androgen excess 3
- Neck circumference: Screens for obstructive sleep apnea risk 1
Screening for Metabolic Syndrome
Three or more of the following criteria warrant this diagnosis 1:
- Waist circumference ≥88 cm for women
- Triglycerides ≥150 mg/dL
- Fasting plasma glucose ≥100 mg/dL
- Blood pressure ≥130/85 mm Hg
- HDL-cholesterol <50 mg/dL in women
Common Pitfalls to Avoid
Do not attribute all weight gain to lifestyle factors alone—secondary causes including hypothyroidism, PCOS, Cushing's syndrome, and medication-induced weight gain must be systematically excluded 2. In women of reproductive age, PCOS is particularly important as obesity worsens the phenotype and fertility outcomes 4.
Review current medications that may contribute to weight gain, including antipsychotics, antidepressants, corticosteroids, insulin, sulfonylureas, and thiazolidinediones 2, 6.
Consider screening for depression or binge eating disorder, as psychological factors frequently contribute to weight gain and difficulty losing weight 2.