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Medline ® Abstract for Reference 31

of 'Rheumatic and bone disorders associated with acromegaly'

Effect of active acromegaly and its treatment on parathyroid circadian rhythmicity and parathyroid target-organ sensitivity.
White HD, Ahmad AM, Durham BH, Chandran S, Patwala A, Fraser WD, Vora JP
J Clin Endocrinol Metab. 2006;91(3):913. Epub 2005 Dec 13.
CONTEXT: Patients with active acromegaly have increased bone turnover and skeletal abnormalities. Biochemical cure of acromegaly may represent a functional GH-deficient state and result in cortical bone loss. Reduced PTH target-organ sensitivity occurs in adult GH deficiency and may underlie the associated development of osteoporosis.
OBJECTIVE: We examined the effect of active and treated acromegaly on PTH concentration and target-organ sensitivity.
PATIENTS: Ten active acromegalic subjects (GH nadir>0.3 mug/liter after 75-g oral glucose load and IGF-I above age-related reference range) and 10 matched controls participated in the study.
DESIGN: Half-hourly blood and 3-h urine samples were collected on patients and controls for 24 h. Samples were analyzed for PTH, calcium (Ca), nephrogenous cAMP (NcAMP, a marker of PTH renal activity), beta C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker). Serum calcium was adjusted for albumin (ACa). Eight acromegalic subjects who achieved biochemical cure (GH nadir<0.3 mug/liter after 75-g oral glucose load and IGF-I within reference range) after standard surgical and/or medical treatment reattended and the protocol repeated.
RESULTS: Active acromegalic subjects had higher 24-h mean PTH, NcAMP, ACa, urine Ca, beta C-telopeptide, and procollagen type I amino-terminal propeptide (P<0.05), compared with controls. Twenty-four-hour mean PTH increased (P<0.001) in the acromegalic subjects after treatment, whereas NcAMP and ACa decreased (P<0.05).
CONCLUSION: Increased bone turnover associated with active acromegaly may result from increased PTH concentration and action. Biochemical cure of acromegaly results in reduced PTH target-organ sensitivity indicated by increased PTH with decreased NcAMP and ACa concentrations. PTH target-organ sensitivity does not appear to return to normal after successful treatment of acromegaly in the short term and may reflect functional GH deficiency.
Department of Diabetes and Endocrinology, Link 7C, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, United Kingdom. h.white@ukf.net