Serum prolactin levels in hypothyroidism

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The association of amenorrhea, galactorrhea, and an elevated serum prolactin level with primary thyroid failure has been reported by several investigators.1–6 We report a case with these findings as well as the serum prolactin levels in 47 additional patients with elevated thyrotrophin concentrations.

Case report

A 24-year-old white woman was examined at the Cleveland Clinic for evaluation of amenorrhea in August 1976. She had cessation of menses 4 years earlier. Following delivery of her only child in 1968, galactorrhea developed and persisted until the time of her evaluation. Facial puffiness, dry skin, and delayed return of deep tendon reflexes were noted. The thyroid gland was not enlarged. Laboratory values are reported in the Table. The galactorrhea ceased and menses resumed within 4 weeks after thyroid replacement therapy with 0.2 mg of L-thyroxine was begun.


Serum prolactin levels were measured in 48 consecutive patients with elevated thyroid-stimulating hormone (TSH) levels. The age range of the 12 male subjects was 7 to 77 years (mean, 53 years) and the age range of the 36 female subjects was 37 t o 84 years (mean, 54 years). Primary thyroid failure was classified into four categories: primary hypothyroidism without goiter (16 patients), Hashimoto’s thyroiditis (22 patients), post 131I therapy (1 patient) and post-thyroidectomy (8 patients). The results shown in Figures 1 and 2 include those of the case reported here in addition to the 47 patients.

Materials and methods

Assays. Serum specimens were assayed in duplicate for prolactin and TSH levels using double. . .



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