Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2012) 29 OC10.3

1Assistance Publique-Hôpitaux de Paris, Hôpital de Bicêtre, Le Kremlin Bicêtre, France; 2Univ Paris-Sud, Le Kremlin Bicêtre, France; 3INSERM, Le Kremlin Bicêtre, France; 4Assistance Publique-Hôpitaux de Paris, Hôpital Européen George Pompidou, Paris, France; 5Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Paris, France.


Background: Hypercalciuria is frequent in patients with acromegaly, but it is unclear how GH/insulin-like growth factor 1 (IGF1) regulate renal calcium handling. Elevated fasting plasma calcium levels despite increased glomerular filtration suggest enhanced renal calcium reabsorption.

Objective: To investigate the impact of acromegaly on phosphocalcium metabolism.

Design: Prospective sequential study (ClinicalTrials.gov Identifier: NCT00531908).

Setting: Tertiary referral medical center and clinical investigation center.

Intervention: 16 consecutive patients (5F/11M) with acromegaly received a single IV infusion of 25 mg of furosemide to induce an acute increase in calcium and magnesium delivery to distal tubular segments during a high-sodium diet with stable dietary calcium, magnesium and phosphate intake.

Measurements: Baseline plasma and urine electrolytes, plasma calcitropic hormones, and furosemide-induced changes in the fractional excretion (FE) of Ca and Mg were measured before and 6 months (range: 1–12) after effective treatment of acromegaly.

Results: Serum IGF1 concentrations normalized in all the patients after acromegaly treatment. Compared with controlled acromegaly, active acromegaly was associated with significantly higher fasting plasma (P=0.0002) and urinary calcium (P=0.0003) levels, lower PTH levels (P=0.0075), higher calcitriol levels (P=0.0137); higher phosphatemia (P<0.0001) and tubular phosphate reabsorption (P=0.0002); similar FGF23 concentrations; and a lower calciuric (P=0.0327) but not magnesiuric response to furosemide.

Conclusion: The IGF1-mediated and PTH-independent increase in calcitriol synthesis in acromegaly is responsible for both absorptive hypercalciuria and increased fasting plasma calcium linked to enhanced distal tubular calcium reabsorption, as shown by the selectively diminished calciuric response to furosemide, that may counteract the effect of increased glomerular filtration and prevent major urinary calcium losses. Physiologically, this calcium-retaining tubular effect of GH/IGF1 would limit calcium excretion during childhood, thus contributing to the positive calcium balance required for juvenile growth.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details are unavailable.

Volume 29

15th International & 14th European Congress of Endocrinology

European Society of Endocrinology 

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