Nephrocalcinosis in Tunisian children

Background: Nephrocalcinosis is rare in children. Its etiologies are multiple. The aim of this study was to analyze the etiology of nephrocalcinosis in Tunisian children

Methods: This retrospective study was conducted in the department of pediatrics in Charles Nicolle Hospital during a period of 10 years [2001-2010]

Results: There were 40 children. The mean age was 3.5 years. The most common signs and symptoms at presentation were growth retardation [42.5%] and hematuria [53.8%]. At presentation, renal failure was detected in 70% of patients. The diagnosis of nephrocalcinosis was performed by ultrasonography. The etiology of nephrocalcinosis included primary hyperoxaluria type 1 [65%] and distal renal tubular acidosis [20%]. A progression to renal insufficiency was observed in 18 cases

Conclusion: Primary oxaluria is the principal cause of nephrocalcinosis; early diagnosis and treatment are mandatory as they help limiting renal function deterioration

Primary hyperoxaluria type 1 in Tunisian children

Primary hyperoxaliuria type 1 is an autosomal-recessive disorder characterized by increasing urinary excretion of calcium oxalate, recurrent urolithiasis, nephrocalcinosis, and accumulation of insoluble oxalate throughout the body. This inborn error of metabolism appears to be a common cause of end stage renal disease in Tunisia. To review the clinical, biological and radiological futures of primary hyperoxaluria type 1 and to correlate these aspects with the development of end-stage renal disease. we retrospectively reviewed 44 children with Primary hyperoxaliuria type I who were treated in our department during a period of 15 years between 1995 and 2009. The diagnosis was established by quantitative urinary oxalate excretion. In patient with renal impairment, the diagnosis was made by infrared spectroscopy of stone or by renal biopsy. Male to female ratio was 1.2. The median age at diagnosis was 5.75 years. About 43% of those were diagnosed before the age of 5 years. Initial symptoms were dominated by uraemia. Four patients were asymptomatic and diagnosed by sibling screening of known patients. Nephrocalcinosis was present in all patients. It is cortical in 34%, medullary in 32% and global in 34%. At diagnosis, twelve children were in end-stage renal disease [27%]. Pyridoxine response, which is defined by a reduction in urine oxalate excretion of 60% or more, was found in 27%. In the majority of patients, the clinical expression of Primary hyperoxaliuria type 1 is characterized by nephrocalcinosis, urolithiasis and renal failure. Pyridoxine sensitivity is associated with better outcome

C telopeptides of type I collagen inpostmenopausal women: an experience in a Tunisian clinical laboratory

The purpose of study was to evaluate the interest of C-telopeptides of type I collagen [CTX] in the diagnosis of osteoporosis in postmenopausal women and to define its cut-off value. A transverse descriptive study enrolled postmenopausal women: 139 osteoporotic [G1] and 39 non osteoporotic [G2]. The 2 groups were defined by bone density measurement. The followmg markers were measured: serum alkaline phosphatase [ALP] bone alkaline phosphatase [bone ALP], serum C-terminal telopeptide of type I collagen [CTX]. Statistical analyses were performed using SPSS 10, 5. The corresponding estimation of sensitivity and specificity of CTX have been presented as receiver Operating Curve [ROC]. There was no difference in the measurement of ALP and bone ALP in the 2 groups but CTX was statistically higher in G1 compared to G2 [p<0.001]. The percentage of osteoporotic women [G1] with CTX values>0.500 ng/ml was higher than that of non osteoporotic women [G2]. We have established a ROC curve to find the cut-off value of CTX that enables the distinction between osteoporotic women with high level of bone remodelling, and non osteoporotic women. The cut-off value of CTX 0.55 pg/mi was the best; it associated best sensitivity and specificity. The total increase and significance for CTX was greater in the group of osteoporotic women and appeared therefore to be a good bone turnover marker in the diagnosis of osteoporosis in comparison with ALP and bone ALP. The cut-off value of CTX 0.55 pg/mi may improve the sensitivity and specificity of prediction of future fractures

[Hypovitaminosis D in Tunisian osteoporotic post menopausal women and its relationship with bone fracture]

The purpose of this study is to evaluate the frequency of hypovitaminosis D in Tunisian osteoporotic women and to search an eventual association between vitamin D status and the fracture risk. A transverse descriptive study enrolled 134 osteoporotic menopausal women aged 50 years or more. We measured calcium, phosphorus, albumin, alkaline phosphatase, creatinine and 25 hydroxyvitamin D [25 [OH] vit D]. Bone mineral density [BMD] was measured for all and osteoporotic women were defined for a T-score of -2,5 or less in the spine, hip or femoral neck .Two groups were defined: G1 with fracture and G2 without fracture .We used SPSS 10.5, X2 tests and a statistical significance level of p< 0,05. Women in G1 [n= 102] were more aged than those in G2 [n= 32] and their menopause was more ancient. Hypovitaminosis D was found in 45,2% of all women, respectively in 50,98% of G1 and 25% of G2. The mean level of vitamin D was more important in G2 [27,5+ 15,1 vs 21,3 + 12,8 ng/ml; p=0,002]. BMD in femoral and lumbar were statistically lower when fractures are present [p< 0,001]. Our study shows that women with hypovitaminosis D [vit D < 20 ng/ml] are prone to osteoporotic fractures. All fracture in community in menopausal women, should be assessed with BMD and screening for 25 [OH] vit D. Increasing life expectancy in our country suggests that this public health problem will grow in the years to come, pointing out the importance of better management of osteoporosis and hypovitaminosis D to prevent fractures

[Interest of bone alkaline phosphatase in hemodialysis patients]

The renal osteodystrophy represent a major complication in haemodialysis. Of this study is to evaluate the value of plasma bone-alkaline phosphatase [bAP] in the diagnosis of the type of renal osteodystrophy among hemodialysis patients and to seek a possible correlation between the bAP, total alkaline phosphatases [tAP] and the intact parathormone [iPTH]. We studied 67 chronic hemodialysis patients. Plasma bAP was determined by immunoenzymatic technic. iPTH [1-84] was measured by electrochimiluminescence. We found that bAP levels were normal 10-20 ng/ml] in 17 patients low [< 10 ng/ml] in 4 and high [> 20 ng/ml] in the 46 other patients. There is a good positive is e correlation between the plasmatic rate of bAP and the following parameters: the period of dialysis [R = 0.316, p = 0,009]. plasmatic rate of tAP [r = 0.781. p < 10[-3]] and the rate of iPTH [r = 0,650]. p < 10[-3]]. There is a good positive correlation between the plasmatic rate of bAP and the rates of the tAP and of iPTH, the correlation between bAP and the ipTh being more significant. A rate of bAP higher than 20 ng/ml had a sensitivity of 93,5% specificity of 63,3% in favour of a rate of iPTH > 400 pg/ml and consequently of the biological diagnosis of hyperparathyroidism. In addition, 4 patients have a bAP < 10 ng/ml with iPTH < 150 pg/ml evoking an adynamic osteopathy. plasma bAP provides useful information about bone remodelling in hemodialysis patients