Protirelin

We aimed to investigate the prevalence and the diagnostic criteria of hypoprolactinemia in patients with panhypopituitarism and the effects of hypoprolactinemia on depression and sexual functions.

Forty-eight patients with panhypopituitarism and 20 healthy volunteers were included. Basal hormone levels were measured and a TRH stimulation test was performed. For the evaluation of sexual functions, questionnaries of Female Sexual Functional Index (FSFI) for females and International Erectile Functional Index for males were performed to the subjects. Depressive symptoms were evaluated by Beck Depression Envontory score (BDI-II).

The peak PRL response to TRH stimulation test at 5th percentile in the control group was 18.6 ng/ml in males and 41.6 ng/ml in females and accepted as the cut-offs for sufficient response of PRL. Prolactin was insufficient in 42(87.5%) patients. A basal PRL level of ≤ 5.7 ng/ml in males and 7.11 ng/ml in females was 100% specific in predicting an inadequate response to TRH stimulation test with 80% and 70% sensitivity respectively. A basal PRL level of ≥ 8.5 ng/dl in males was 100% specific and 76% sensitive, and in females a level of ≥ 15.2 ng/dl was 96% specific and 66% sensitive in predicting an adequate response to TRH. PRL deficient patients with panhypopituitarism had higher depression scores compared to the controls, lower sexual function scores in males.

PRL deficiency is prevalent among individuals with panhypopituitarism, with the potential to result in elevated depression scores in both sexes and impaired sexual functions in males. A basal PRL level seems to be sufficient for the diagnosis of hypoprolactinemia in routine clinical practice.

A 4-day-old infant was admitted for neonatal jaundice. He had persistent tachycardia and tachypnea. Initial workup showed a serum free T4 of 75.6 pmol/L (5.87 ng/dL) (reference range: 11.5-28.3 pmol/L; 0.89-2.20 ng/dL) and a nonsuppressed TSH 3.76 mIU/L (reference range: 0.72-11.0 mIU/L). A TRH stimulation test showed an exaggerated TSH response with a peak of 92.1 mIU/L at 30 minutes after TRH injection, which suggested the diagnosis of resistance to thyroid hormone β syndrome. Sanger sequencing showed a questionable pathogenic variant in the THRB gene with low signal amplitude. Restriction fragment length polymorphism was consistent with its presence. The variant was originally reported as heterozygous. Next-generation sequencing was performed on blood and buccal swab samples of the patient and his parents, which confirmed this de novo mosaic variant NM_000461.5:c.1352T > C p.(Phe451Ser) in the patient but not in his asymptomatic parents. As it was in a mosaic state, only the offspring, but not other first-degree relatives, of the patient would have the risk of inheriting that variant.