Pancytopenia in the first trimester: An indicator of hidden hyperthyroidism

Area of Science:

• Endocrinology
• Hematology
• Obstetrics

Background:

• Pancytopenia, a rare condition in the first trimester of pregnancy, presents a diagnostic challenge.
• Hyperemesis gravidarum can cause significant maternal weight loss and nutritional deficiencies.

Observation:

• A 33-year-old pregnant woman at 9 weeks gestation presented with severe hyperemesis gravidarum and pancytopenia (WBC 3500/μL, Hb 9.8 g/dL, platelets 10.5 × 10(4)/μL).
• Extensive investigations revealed suppressed thyroid-stimulating hormone (<0.02 μU/mL) with elevated free triiodothyronine (11.25 pg/mL) and free thyroxine (4.74 ng/dL), alongside positive anti-thyroid-stimulating hormone receptor antibodies (12.2 IU/L), confirming true hyperthyroidism.

Findings:

• Treatment with propylthiouracil (300 mg/day) initiated at 10 weeks gestation led to the normalization of blood counts by 12 weeks gestation.
• Concurrently, thyroid hormone levels (free triiodothyronine and free thyroxine) returned to normal ranges.

Implications:

• This case suggests that hyperthyroidism should be considered in the differential diagnosis of unexplained pancytopenia during the first trimester of pregnancy.
• Early diagnosis and management of hyperthyroidism can resolve hematological abnormalities and improve maternal and fetal outcomes.