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Medline ® Abstract for Reference 31

of 'Rheumatic and bone disorders associated with acromegaly'

31
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Effect of active acromegaly and its treatment on parathyroid circadian rhythmicity and parathyroid target-organ sensitivity.
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White HD, Ahmad AM, Durham BH, Chandran S, Patwala A, Fraser WD, Vora JP
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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.
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Department of Diabetes and Endocrinology, Link 7C, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, United Kingdom. h.white@ukf.net
PMID