Marie‐M. Couttenye

Bio: Marie‐M. Couttenye is an academic researcher from University of Antwerp. The author has contributed to research in topics: Renal osteodystrophy & Osteomalacia. The author has an hindex of 4, co-authored 4 publications receiving 292 citations.

Spectrum of renal bone disease in end‐stage renal failure patients not yet on dialysis

Abstract: Background During the last few years the spectrum of renal osteodystrophy (ROD) in dialysis patients has been studied thoroughly and the prevalence of the various types of ROD has changed considerably. Whereas until a decade ago most patients presented with secondary hyperparathyroidism (HPTH), adynamic bone (ABD) has become the most common lesion within the dialysis population over the last few years. Much less is known about the spectrum of ROD in end-stage renal failure (ESRF) patients not yet on dialysis. Methods Transiliac bone biopsies were taken in an unselected group of 84 ESRF patients (44 male, age 54+/-12 years) before enrolment in a dialysis programme. All patients were recruited within a time period of 10 months from various centres (n=18) in Macedonia. Calcium carbonate was the only prescribed medication in patients followed up by the outpatient clinic. Results HPTH was found in only 9% of the patients, whilst ABD appeared to be the most frequent renal bone disease as it was observed in 23% of the cases next to normal bone (38%). A relatively high number of patients (n=10; 12%) fulfilled the criteria of osteomalacia (OM). Mixed osteodystrophy (MX) was diagnosed in 18% of the subjects. There was no significant difference between groups in age, creatinine, or serum and bone strontium and aluminium levels. Patient characteristics associated with ABD included male gender and diabetes, whilst OM was associated with older age (>58 years). Conclusions In an unselected population of ESRF patients already, 62% of them have an abnormal bone histology. ABD is the most prevalent type of ROD in this population. In the absence of aluminium or strontium accumulation the relatively high prevalence of a low bone turnover as expressed by either normal bone or ABD and OM is striking.

Use of the low-dose desferrioxamine test to diagnose and differentiate between patients with aluminium-related bone disease, increased risk for aluminium toxicity, or aluminium overload

Abstract: Background. Aiming at a safe method in the diagnosis of aluminium-related bone disease (ARBD)/aluminium overload the low-dose desferrioxamine (DFO) test was developed. In a multicentre study histological and histochemical data and aluminium bulk analysis of bone biopsies of 77 dialysis patients were correlated with the results of both the 5 mg/kg and 10 mg/kg DFO tests. Methods. ARBD was considered to be present when >15% of the bone surface was positively stained for aluminium and the bone formation rate was below 220 μm 2 /mm 2 /day. Patients in which the Aluminon® staining was positive (>0%) were considered at an increased risk for aluminium toxicity independent of the type of renal osteodystrophy. Patients were considered aluminium overloaded when the bone aluminium content was >15 μg/g wet weight and/or the Aluminon® staining was positive (>0%). Results. Using the proposed criteria 15 patients were found to have ARBD ; 13 of them presenting with a serum iPTH below 150 ng/l. In conjunction with an iPTH measurement the DFO test had a more than acceptable sensitivity and specificity in the diagnosis of ARBD. The test was considered positive when a post-DFO serum aluminium increment (ΔsAl) above 50 μg/l (5 mg/kg) or 70 μg/l (10 mg/kg) together with a serum iPTH below 150 ng/l was found. Using these cut-off levels the 5 and 10 mg/kg tests in the diagnosis of ARBD had a sensitivity of 87% and a specificity of 95% and 92% respectively whereas the predictive value for a positive test for the population under study was 80% (5 mg/kg). Not a single patient with a serum iPTH >650 ng/l had a positive staining (>0%) even when the bone aluminium level was elevated (> 15 μg/g wet weight). In the detection of patients at risk for aluminium toxicity ΔsAl thresholds of 50 μg/l (5 mg/kg) and 70 μg/l (10 mg/kg) in combination with a serum iPTH < 650 ng/l had a sensitivity of 92% and specificity of 86% and 84% respectively. In the clinical setting of aluminium overload, threshold ΔsAl levels of 50 μg/l (5 mg/kg) and 70 μg/l (10 mg/kg) had a sensitivity of 91% and a specificity of 95% and 90% respectively. Conclusions. The low-dose DFO test is a reliable test for the detection of aluminium overload ; however, it is not specific enough to differentiate between ARBD, increased risk of aluminium toxicity, and aluminium overload unless it is used in combination with a serum iPTH measurement. In conjunction with a serum iPTH measurement it is an important tool in the differential diagnosis and may avoid the necessity of a bone biopsy in the majority of patients. Data obtained in the present study have allowed us to update the strategies for monitoring, diagnosis and patient follow-up proposed at the Consensus Conference on Diagnosis and Treatment of Aluminium Overload in End-Stage Renal Failure ; Paris, 1992.

Mechanisms of action and therapeutic potential of strontium in bone

Abstract: The processes of bone resorption and formation are tightly governed by a variety of systemic and local regulatory agents. In addition, minerals and trace elements affect bone formation and resorption through direct or indirect effects on bone cells or bone mineral. Some trace elements closely chemically related to calcium, such as strontium (Sr), have pharmacological effects on bone when present at levels higher than those required for normal cell physiology. Indeed, strontium was found to exert several effects on bone cells. In addition to its antiresorptive activity, strontium was found to have anabolic activity in bone, and this may have significant beneficial effects on bone balance in normal and osteopenic animals. Accordingly, strontium has been thought to have potential interest in the treatment of osteoporosis. This review summarizes the mechanisms of action of strontium on bone cells, the evidence for its beneficial effects on bone mass in vivo, and its potential therapeutic effects in osteopenic disorders.