The effect of sampling time of prolactin in diagnosis of hyperprolactinemia in suspected patients

Because prolactin secretion varies during the day and changes in serum prolactin also occur from pathophysiologic and laboratory causes, thus a single blood sample is not enough to determine the exact amount of prolactin secretion. The aim of this study is evaluation of prolactin changes between the early hours of the morning and evening in patients with suspicious and uncertain symptoms of hyperprolactimenia (lack of galactorrhea) that refer to the laboratory to determine the status of borderline values and mild elevation( less than twice the normal upper limit ) of prolactin. Method: In patients with symptoms suspected to hyperprolactimenia that early morning serum prolactin levels of them were higher than normal a new sample was carried out in the evening. Patients with a clinical history of hyperprolactinemia, pituitary adenoma( in imaging study ) and galactorrhea were exclude from this study. Results: From 115 patients with morning hyperprolactinemia, 52(41.71%) women and 2 (33.33%) men have normal evening prolactin levels and in 57(58.29%) women and 4 (66.67%) men evening prolactin levels remain high. The mean percentage of reduction in evening prolactin levels compared to the morning, in women with normal evening prolactin levels is significantly more than women who have high evening prolactin levels. In 30.77% of women(52 patients) who had normal evening prolactin, mean prolactin levels of morning and evening were normal. Conclusion: Morning prolactin level of patients is significantly higher than evening. In about half of the patients with morning hyperprolactinemia, evening prolactin levels return to normal and shows that if the benchmark of treatment was only morning prolactin level, half of the patient may be treated incorrectly. If morning prolactin is increased up to about twice the normal upper limit, in more than 40 percent measurement of evening prolactin reveals the falseness of elevated morning prolactin. Also, using of average morning and evening prolactin instead of a single measurement reduces the possibility of false positive but not in most cases, so it cannot be a safe alternative. Evening prolactin levels decreased significantly in women more than men that shows the importance of re-measurement of prolactin in women.

کلیدواژه ها:

Prolactin ، sampling time