Evaluation of serum prolactin level in patients of subclinical and overt hypothyroidism.

Abstract

Prolactin secretion is controlled by prolactin inhibitor factor that is secreted from hypothalamus; factors like vasoactive inhibitory peptide (VIP) and thyroid releasing hormone (TRH) lead to increase in prolactin secretion. Hyperprolactinemia is a common condition that can result from a number of causes including hypothyroidism. Objective of the study was to determine correlation between serum levels of prolactin and thyroid hormones in euthyroid, subclinical and overt hypothyroid cases. Consecutive patients presenting for various thyroid related problems were segregated into two groups subclinical and overt hypothyroidism according to their diagnosis based on history and clinical examination, laboratory reports, inclusion and exclusion criteria. Newly diagnosed 75 patients in each group were finally enrolled. Similar number of age and sex matched controls were selected. All subjects filled a predesigned questionnaire for the evaluation of hypothyroid symptoms. Thyroid profile for T3, T4 (total and free), TSH and prolactin were determined in all the subjects and analyzed. Prolactin elevation was found in 16 patients (21.33 %) with overt hypothyroidism, and in six patients (8%) with subclinical hypothyroidism. The control group and subclinical hypothyroid patients exhibited no significant difference in terms of total and free T3, total and free T4. For TSH and prolactin on the other hand, a statistically significant elevation was found in patients with overt hypothyroidism when compared with subclinical hypothyroidism; and in patients with subclinical hypothyroidism when compared to the controls. A significant statistical difference was observed between the two groups of hypothyroid patients for all hypothyroid symptoms except alopecia and hirsuitism. The incidence of hyperprolactinemia in hypothyroidism was found to be higher when compared with normal controls. Serum prolactin assessment should be performed on all patients with hypothyroidism (overt and subclinical) before performing further tests.