High prevalence of hypothyroidism in patients with primary pulmonary hypertension

To characterize the prevalence of hypothyroidism in a population with primary pulmonary hypertension (PPH).

Retrospective record review of 41 patients with PPH seen between 1991 and 1997 at a tertiary care center. Data abstracted included: history of previous thyroid disease, intake of thyroid supplement, and thyroid function tests. Hypothyroidism was defined as a serum thyroid stimulating hormone (TSH) level higher than 5.5 U/L, intake of thyroid supplement, or low serum thyroxine level.

Of the 40 patients with PPH included in the study (11 men and 29 women), ages ranged from 11 to 76 years (mean 43.5 years). The mean pulmonary artery pressure was 58.7 mm Hg. Thirty-three patients had normal serum TSH levels (3 of whom were on levothyroxine supplement); 1 had low TSH; 5 had high TSH (range, 6.8-9.9 U/L, mean 8.4 U/L), and 1 had low thyroxine (T4 < 1.0 microg/dL). Nine of 40 patients (22.5%) had evidence of hypothyroidism, which is much more than expected in the general population of similar age range (2.8% in men, 7.5% in women) (p = 0.002).

The prevalence of hypothyroidism in patients with PPH is high (22.5%). Patients with PPH should be investigated for the possibility of coexisting hypothyroidism.