Author's Reply: The curious case of prolactin hormone.

Sir,

We are highly thankful to the authors for evincing such an interest in our article entitled “Serum prolactin levels in psoriasis and its association with disease activity: A case control study.” We would like to answer the queries put forth by the authors in a sequential manner.

To establish the diagnosis of hyperprolactinemia, a single measurement of serum prolactin (PRL); a level above the upper limit of normal confirms the diagnosis as long as the serum sample was obtained without excessive venipuncture stress.[1] In our study, the blood samples of the participants were taken per these recommendations

The exclusion criteria in our study were pregnancy, breastfeeding, and evidence of renal, hepatic, endocrinopathy (prolactinoma, hypothyroidism), and psychiatric disease, as well as patients who were receiving any medications affecting prolactin (PRL) levels. The main aim of such exclusions was to avoid instances of secondary hyperprolactinaemia. In our study, hypothyroidism was excluded not only by history and clinical examination, but also by thyroid function testing

It is uncertain whether the amount of estrogens in hormonal contraceptives is able to induce hyperprolactinemia. In general, estrogen substitution and oral contraception have no or only a minimal effect on PRL levels[2]

Anticonvulsant administration is also not a very common cause of hyperprolactinemia. One case report documented hyperprolactinemia during chronic anticonvulsant therapy with phenytoin and phenobarbital after the addition of oral fluoresone 750 mg daily.[3]

Emotional disturbances are one of the most important causes of hyperprolactinaemia, and stress is significantly associated with exacerbations of psoriasis, thus secondary hyperprolactinaemia due to stress cannot be excluded[4]

Vigorous exercise should be avoided for at least 30 minutes before checking PRL levels.[5] In our study, the participants were made to rest for 30 minutes before taking the blood sample

Coitus is another physiological cause of hyperprolactinemia. Kruger et al., have demonstrated that sexual intercourse with orgasm induced an immediate increase in the PRL levels.[6] Before initiating this study, all these things had been kept in mind, but in the conservative society of Kashmir, asking the history of coitus on the night prior to sample collection was practically difficult.

The gold standard for the diagnosis of macroprolactinemia is gel-filtration chromatography, but because this method is laborious and expensive, polyethylene glycol (PEG) serum precipitation has been widely used as a screening method.[7] However, because of the lack of such expertise, the conventional method of prolactin estimation was used

There are studies that have shown a reduction in PRL secretion or levels following systemic administration of steroids.[8] So, if steroids were to be applied over larger body surface areas, consequent systemic absorption may affect serum PRL levels. In order to avoid that confounding factor, serum PRL levels in our patients were measured before and after treatment with tacalcitol ointment once a day for 6 weeks.

We once again thank the authors for their in-depth analysis of our article and their valuable inputs.