ÖZET
Bu çalıflmada kronik böbrek yetmezliği olan olgularda renal osteodistrofinin erken tanısında faydalı olabilecek radyolojik ve biyokimyasal parametreleri prospektif olarak arafltırmayı planladık.
Kronik böbrek yetmezliği nedeni ile hemodiyalize giren 50 olgu ve dahil edildi. Böbrek problemi ve kemik hastalığı olmayan 50 olgu kontrol grubu olarak çalıflmaya dahil edildi. Serum kalsiyum, fosfor, alkalen fosfataz,b-microglobulin (bm), osteokalsin (BGP), intact parathormon (iPTH) seviyeleri ölçüldü.Her iki grupta sağ el grafileri magnifiye teknikle çekildi. Lomber vertebra ve femur boyun kemik mineral yoğunluğu (KMY) DEXA yöntemi ile ölçüldü.
Olgularımızın ortalama hastalık süresi 8,38±5,61 yıl, diyalize girme süresi 6,9±4,01 yıldı. Kalsiyum dıflındaki bütün biyokimyasal parametlerde olgu ve kontrol grubumuz arasında önemli derecede fark mevcuttu (p<0,05).İPTH ve KMY arasında negatif korelasyon mevcuttu (r=-0,4, p<0,05). İPTH ve BGP, İPTH ve b2 m arasında pozitif korelasyon mevcuttu (r=0,6, p<0,05), (r=0,5, p<0,05). Diyaliz süresi ve femur boyun KMY arasında istatistiksel olarak anlamlı, düflük düzeyde negatif korelasyon mevcuttu (r=0,2,p<0,05). Diyaliz süresi ve İPTH, diyaliz süresi ve bm arasında pozitif korelasyon mevcuttu (r=0,3, p<0,05),(r:0.4, p<0,05).El grafilerinde osteopeni ve subperiostal resorbsiyon, radyal arter kalsfikasyonu ve endosteal resorbsiyon görüldü. Olgularımızın %80’de osteopeni, %58’de subperiostal resorbsiyon saptandı. İPTH seviyesi 200 pg/ml üzerinde olan olgular ve osteopenisi olan olgularda RO tanısı için sensitivite %93, spesifite %92’dü. Yüksek İPTH-BGP için sensitivite ve spesifite sırası ile %90,3 ve %87 ‘di. Yüksek İPTH-subperiostal resorbsiyon için ise sensitivite %83,9, spesifite %84,2 ‘di.
İPTH, BMD, BGP ölçümleri ve el grafilerinin değerlendirilmesi RO‘nin erken tanısı ve izleminde kullanılabilir. (Türk Osteoporoz Dergisi 2013;19: 7-11)
Introduction
The number of patients with chronic renal failure (CRF) is increasing with the development of new diagnostic methods. Although the average life span of the patients with CRF has increased with treatment modalities such as hemodialysis and peritoneal dialysis, many complications began to be seen more frequently. Renal osteodystrophy (RO) is one of these complications and it causes mineral and bone metabolism impairment, and morbidity and mortality in most of patients (1-3). Osteitis fibrosa sistica, osteomalacia, skeletal abnormalities related to β2 mikroglobulin (β2 m), osteosclerosis and osteoporosis are histopatologically observed in RO (4). Hypocalcemia, phosphate retention, changes in vitamin D metabolism, decrease of PTH degradation, changes in calcium regulation are led to secondary hyperparathyroidism pathophysiologically. Increase of PTH levels results in rise of osteoclastic activity and bone resorption. Such an osteoclastic activity occurs in Haversian channels of cortical bone and subperiostal and endosteal surfaces. Cortical bone resorption occurs with PTH stimulated increased osteosit activity. Possible causes of osteoporosis in CRF include changes in vitamin D levels, immobilisation and chronic protein deficiency. Hyperphosphatemia can be observed in the phases which the catabolism increases due to the protein metabolism and catabolism. RO which becomes clinically evident with cases like bone aches, myopathy, muscle cramps, calciphylaxis and skeleton deformities affects the life quality of the cases with CRF and causes serious mortality and morbidity (5). Bone biopsy is advised for definitive diagnosis but its usage is limited due to its invasive process (6). That’s why evaluation of the current laboratory and scanning procedures and not skipping the RO diagnosis are of the importance (7). For this reason in this prospectively planned study, we aimed to investigate the noninvasive methods that can be useful in early diagnosis of RO.
Material and Method
Fifty patients on chronic hemodialysis were included in this study which was planned prospectively in order to examine RO with noninvasive methods in the patients on hemodialysis. Fifty voluntary subjects without any primary renal problem and bone disease were also included in this study as a control group. The physical examinations of members of both patient and control groups were performed. The serum calcium, phosphorus, alkalen phosphatase, β2 mikroglobulin (β2 m) and intact parathormon (iPTH) levels of both groups were measured. Osteocalcin (BGP) levels were determined by Enzyme-linked immunosorbent assay (ELISA) method.
Right hand graphies of both case and control groups were taken by magnifying techniques. Thereafter, bone mineral dansities were measured from lumbar vertebra and femur neck by Dual energy X-ray absorptiometry (DEXA) method.
T-test, chi-square test and Pearson correlation analysis were used for statistical analysis of study parameters of patient and control groups. Statistically p<0.05 value was considered as significant.
Results
The average age of our cases; 30 of whom were male, whereas 20 of whom were female; was 46.4±11.5 (19-69) years. The average disease duration of our cases was 8.38±5.61 (1-23) years and the duration of hemodialysis was 6.9±4.01 (1-16) years. Thirty-one members of the control group were male and 19 of them were female, and their average age was 45.8±11.5 (25-66) years. “There was no significant difference between case and control groups in age and sex distribution (p>0.05). The distribution of cases according to etiologies were shown at Graphic 1.
The average and standart deviation values of alkalen phosphatase (ALP), calcium, phosphorus, β2-microglobulin, osteocalcin (BGP) and parathormon of cases and controls were given at Table 1. There was significant difference between case and control groups in all biochemical parameters, except calcium levels (p<0.05).
The bone mineral densities of femoral neck and lumbar vertebra were measured in both groups; and Z-value and T-value were calculated. Both of lumbar vertebra (BMDL) values and femoral neck (BMDF) values have shown significant difference between two groups ( p<0.05) (Table 2).
The correlation of iPTH with BMD, BGP, ALP and β2 m were examined, there was negatif correlation between iPTH and BMD (r=-0.4, p<0.05), whereas, there were positive correlations between iPTH and BGP (r=0.6, p<0.05), and between PTH and β2 m (r=0.5, p<0.05).
When the correlations of dialysis duration with BMDF, BMDL, iPTH, BGP, ALP and β2 m were evaluated, there was low level but statistically significant negative correlation between dialysis duration and BMDF (r=-0.2, p<0.05), whereas, there were positive correlation between dialysis duration and PTH (r=0.3, p<0.05) and between dialysis duration and β2 m (r=0.05, p<0.05) (Table 3).
The right hand (dominant hand) graphies of all patients in both case and control groups were evaluated radiologically (Figure 1). The hand graphies were prepared by a special magnifying technique. Osteopenia and subperiostal resorption were found to be most frequent findings. Less frequently, radial artery calcification and endosteal resorption were determined. Osteopenia was found in 80% of cases, and subperiostal resorption were determined in 58% of cases (Table 4). Subperiostal resorption were frequently determined at radial, ulnar and radioulnar sites of phalanges (Graphic 2).
For diagnosis of RO occuring as a result of secondary hyperparathyroidism, we investigated the sensitivity and specificity values of parameters evaluated in our cases. When we take into account osteopenia cases which have iPTH values higher than 200 pg/ml, we determined sensitivity as 93% and specifity as 92%. By such a similar evaluation, the sensitivity was 90.3% for high iPTH-BGP levels, whereas specifity was 87%. In the presence of high iPTH values and the subperiosteal resorption, the sensitivity and specifity were found 83.9 and 84.2%, respectively.
