ABC of prolactin hormones

PRL:-  Source ?? Secreted from 1) ant Pituitary by Lactotrophs compromise about 15-25% of entire adenohyphophysis. 2) some other parts of brain 3) Lymphocytes (PRL- helps in immune functions of the body).4) Controls autocrine & paracrine functions of many cells.5) like growth hormone and hPL it also control- angiogenic activities. 6) May have actions on Breast Ca & prostate ca.

Secretion: - its tonic secretion is controlled by PIF (Dopamine).Oestrogen promotes synthesis and release of PRL. In peripheral ovulatory period when E2 is high PRL will be high.

Progesterone depresses serum PRL- abd oestrogen stimulates its after stoppage of ocp-

THE SERUM LEVEL SCOMES DOWN TO NORMAL AFTER 3-4 DAYS.

Circadian Rhythm: Diurnal variation:-

Pulsatile release: In late follicular phase 14 pulses per day and in late luteal phase the total pulse per day is 9/ daily. Each pulse last for 70 minutes and with an inter-pulse interval of about 70 minutes.

Factors causing rise of PRL: - Stress, Smell (Olfaction), Audition-Noise, But Chr, stress & exercise do not cause rise of PRL. Breast stimulation. Venepuncture.

When to collect samples? Mid morning, no physical examination.

Suppose report come high: What next?

a)                 Is she already pregnant: - In preg due to high rise of E2à start rising at 6-8 weeks of preg—surprisingly, regardless of breast feeding PRL comes to normal 6 weeks after delivery. So Postpartum contraception should begin after 6 weeks as Ovulation can occasionally occur.

b)                MICROADENOMA.

c) 

Of all pit adenomas 30-40% if al Pit adenomas, & 10% of all intracranial neoplasms. There is one syndrome called Type 1 Syndrome where genetic change is that there are multiple endocrine tumours in the same person. Most Lactotrophs tumours are benign. If adenoma size is < 1 cm the n usual serum level is 200 ng/ml. but if size is 1 cm to 2 cm in diameter than PRL vale may exceed 1000 ng/ml/Above such dia the level can be higher still.

Pitfalls in the assay report:-

1)           If cystic adenoma-then serum level may not correlate with the size of tumour.

2)           Artifact in the immunoradiometric assay.-if too low in a case of tumour then dilutes the sera- will yield appropriate result. (Hook effect).

3)           Any disease or tumour near Hypothalamus can impede secretion of PIFà rise of PRL. Head trauma, Craniopharyngioma, infiltrative diseases if brain, Kochs, malig deposits.

4)           Hypothyroidism- Hypothyroidism per see usually do not cause rise of basal PRL. What happens is that in cases of hypothyroidism if TRH is administered as a challenge dose then PRL will rise. due to the effect of raised TRH. MRI of Pit may be solo enlargement of thyrotrophic adenoma and not Lactotrophs adenoma.

5)           Pharmacological agents causing Hyperprolactinaemia:-

6)           Resperidone, olanzapin, phenothiazine, Clomipramine, pimozide, haloperidol, & domperidone. Four days after Ry stoppage of this drugs the PRL will hopefully come to normal. Additionally, MAO inhibitors (pargyline, clorgyline,   opiate antidepressants codeine, Desipramine, Amitryptiline, Clomipramine all can raise of PRL...

PRL in Males

PRL is found in high conc in semen and helps in Spermatozoal metabolism à Glucose oxidation, Fructose utilization, Glycolysis.