Prevalence and Risk Factors of Nephrocalcinosis in Children at Sohag University Hospital

Nephrocalcinosis (NC) is characterized by deposition of calcium salts in the renal parenchyma. It is classified by ultrasonography into three types: cortical, medullary, and diffuse nephrocalcinosis . Cases of nephrocalcinosis in children are increasing and are becoming common causes for hospital admissions or visits to renal clinics. In addition, it is associated with significant long-term sequelae, including morbidity caused by recurrent stones as well as the development of chronic kidney disease (CKD).

The exact pathogenesis of nephrocalcinosis remains under investigation, in medullary nephrocalcinosis the main cause is hypercalciuria. Increased urinary calcium load arises either through increased calcium absorption (extra-renal causes) or impaired calcium reabsorption within the renal tubule . The majority of calcium reabsorption (~65%) occurs in the proximal tubule, and (~25%) is reabsorbed in the thick ascending limb of the loop of Henle and (~5%) is reabsorbed from the cortical collecting duct . Identification of monogenic causes of nephrocalcinosis affecting these areas has provided valuable insights into the pathogenesis of this heterogeneous condition. Interestingly, although a further (~7-10% (of calcium is reabsorbed within the distal convoluted tubule, no monogenic causes of nephrocalcinosis have been identified which affect this section of the renal Tubule . Nephrocalcinosis can occur due to various metabolic or renal tubular disorders, Vitamin D excess, medication, and prematurity .

The condition can progress to chronic kidney disease (CKD), and the renal prognosis is determined by its underlying cause, so a diagnostic evaluation in all children with NC to determine its causes and preserve kidney function is mandatory . Since the use of kidney ultrasound (US) as a routine diagnostic procedure, NC is detected in growing numbers of children. There is Different incidence rates and etiologies are reported in children with NC, reflecting the difference in geographic, genetic, and socioeconomic back ground.

Classifications of NC, based on its US appearance, have been proposed, distinguishing medullary, cortical and global NC . It has also been stated that whether NC is harmful or not depends on its magnitude, and on whether it is the result of an ongoing problem or of a transient insult .

Diagnosis of nephrocalcinosis is important to stop progression of renal injury. A detailed history should be obtained, including birth history, diet, fluid intake, medications, vitamin supplementation, developmental history, and other known diseases or conditions. A detailed family history also is very important. Physical examination findings are typically nonspecific, but the presence of signs that are syndromic in nature may provide helpful information to narrow the differential diagnosis .