Hyperprolactinemia is rare and of minor
clinical importance in patients with hypothyroidism
(March 2003)
The background of
the study. Patients with hypothyroidism may have high serum
prolactin concentrations (hyperprolactinemia), which can cause reproductive
disorders. In this study, the frequency of hyperprolactinemia in
a large group of patients with hypothyroidism and its impact on
the patients’ reproductive function were assessed.
How the study was done. One thousand
three patients (938 women, 65 men) with hypothyroidism were studied.
Among them, 93 patients had high serum thyrotropin (TSH) and low
serum thyroxine (T4) concentrations (overt hypothyroidism) and 910
patients had high serum TSH and normal serum T4 concentrations (subclinical
hypothyroidism). Serum prolactin was measured once in all patients.
The results of the study. Hyperprolactinemia
was found in 8 percent of the women and 8 percent of the men. The
frequency was similar in the patients with overt hypothyroidism
(10 percent) and those with subclinical hypothyroidism (8 percent).
The mean serum prolactin concentration was 49 ng/ml in the women
with hyperprolactinemia (normal, <20 ng/ml) and 33 ng/ml in the
men with hyperprolactinemia (normal, <18 ng/ml). There was no
correlation between serum prolactin and TSH concentrations.
Seventeen (36 percent) of the premenopausal women with hyperprolactinemia
had infrequent or no menstrual periods, as compared with 68 (16
percent) of the premenopausal women with normal serum prolactin
concentrations. No woman who was not pregnant or nursing an infant
was producing milk.
The conclusions of the study. Hyperprolactinemia
is rare in patients with hypothyroidism, and most premenopausal
women with hypothyroidism and hyperprolactinemia have normal menstrual
cycles.
The original article. Raber W, Gessl
A, Nowotny P, Vierhapper H. Hyperprolactinaemia in hypothyroidism:
clinical significance and impact of TSH normalization. Clin Endocrinol
2003;58:185-91.
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