PTHrP related hypercalcemia during pregnancy: an overshoot of normal physiology?

EM Winter, N.M. Appelman-Dijkstra

Woensdag 20 april 2016

15:10 - 15:20u in Auditorium 2

Categorie├źn: Parallelsessie

Parallel sessie: Parallelsessie 2: Case reports/research

A 32-year old female presented in her 15thweek of pregnancy with nephrolithiasis. Laboratory investigation showed hypercalcemia (calcium 3.37 mmol/L) with severe hypercalciuria, and suppressed parathyroid hormone (PTH 2 cup sizes), we hypothesized that PTHrP overproduction might be related to this augmentation. A rise in PTHrP is a physiological phenomenon during pregnancy, being produced in growing placental and mammarian tissue. Rising prolactin causes breast augmentation as preparation for lactation. The enormous increase in dense breast tissue, also called gigantomastia, was caused by increased prolactin sensitivity rather than high prolactin values, since prolactin was according to pregnancy term. This gigantomastia caused increased PTHrP production. This phenomenon has been described in relation to estrogens (juvenile gigantomastia) as well. Treatment with dopamine agonist was started, diminishing prolactin and PTHrP levels (undetectable), but, most importantly, normocalcemia throughout rest of pregnancy. After 39 weeks a healthy boy with normal birth weight and calcium values was born. The dopamine agonist was stopped without recurrence of detectable PTHrP or hypercalcemia.

Conclusion: Physiological adaptations might sometimes cause exaggerated responses by increased hormone sensitivity. In this case increased prolactin sensitivity caused gigantomastia of pregnancy which resulted in PTHrP overproduction, leading to symptomatic hypercalcemia. This could be normalized by simply decreasing prolactin and thus PTHrP level by dopamine agonists.