International Journal of Critical Illness and Injury Science

: 2015  |  Volume : 5  |  Issue : 3  |  Page : 216--217

Renal leak; mechanism of hypercalciuria in short-term immobilization

Majid Malaki 
 Assistant Professor of Pediatric Nephrology, Pediatric Health Research Centre, Tabriz University of Medical Science,Tabriz, Iran

Correspondence Address:
Majid Malaki
Pediatric Health Research Centre, Tabriz University of Medical Science, Tabriz

How to cite this article:
Malaki M. Renal leak; mechanism of hypercalciuria in short-term immobilization.Int J Crit Illn Inj Sci 2015;5:216-217

How to cite this URL:
Malaki M. Renal leak; mechanism of hypercalciuria in short-term immobilization. Int J Crit Illn Inj Sci [serial online] 2015 [cited 2022 Sep 29 ];5:216-217
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Dear Editor,

Hypercalciurai is daily urine excretion of calcium beyond 4 mg/kg or calcium to creatinine excretion over 0.21 randomly. [1] Hypercalciuria incidence in healthy children varied. [2] immobilization is a common cause of hypercalciuria. [3] We studied 40 critically ill children were immobilized and starved for their disease. In short term (5 days), their serum calcium in both total (8.4 ± 0.8 vs 8.6 ± 0.6 mg/dl) and ionized (4.1 ± 0.4 vs 4.2 ± 0.3 mg/dl) was not changed while serum phosphor decreased significantly, it was 0.5 mg/dl in average (4 ± 1 vs 3.5 ± 0.8, P 0.02). Calcium excretion in 1 st day in compared to control was (0.31 ± 0.3 vs 0.1 ± 0.08, P 0.03). This measure in 5 th day of observation was (0.37 ± 0.4 vs 0.1 ± 0.08, P 0.003) Hypercalciuria occurs in 10% of control group and 51% in 1 st day (0.001) and 54% in 5 th day. Urinary sodium excretion in cases with hypercalciuria was higher but the excretion rate was more significant in 1 st day compared to 5 th day. In contrast to 1 st day of observation in 5 th day, hypercalciuria occurred more significant in lower age [Table 1]. Resorptive hypercalciuria in immobilization may happens due to parathyroid and 1-25 dihydroxyvitamin D axis mechanism. [4] The time for hypercalciuria evolving is short because in a case report in a 10-year-old boy nephrolithiasis was observed after immobilization for 8 days. [3] As our study in critical ill child hypercalciuria occurs so soon in 1 st days of disease in near half of cases while the serum calcium both total and free part were not differed in both hypercalciuric and normal calcium excreted groups. In fact, this show that mechanisms of hypercalciuria in immobilized ill children is a common and complex matter beyond that theories which suggested earlier, it may be due to increase serum cytokine levels which derange calcium metabolism in inflammatory conditions by secretion of interleukin1 and tumor necrosis factor-α which play role in bone resorption in special conditions like as malignancies. [5] Other studies in adults describe hypercalciuria starts at 4 th week of immobilization the mechanism of hypercalciuria in this group people are attributed to resorptivehypercalciuria which lead to hypercalcemia, hyperphosphatemia beside to renal phosphor threshold and in prolonged time with decrease renal function calcium filtration decreases which aggrevate hypercalcemia. [4] We show hypercalciuria appear short term after immobilization and serum calcium both total and free not changed. Serum phosphor also drops 0.5 mg/dl in 5 days without effecting in hypercalciuria incidence or severity which is not related to reabsortive phenomena because all patients were starved or resorptive as serum calcium was not changed and activation of parathyroid axis activity takes time to activate while renal leak hypercalciuria mechanism by act of unknown mechanism like as cytokines similarly to what occur in malignancies [5] can be involve in this phenomena which lower age are more vulnerable to hypercalciuria in longer immobilization 5 days as our study.{Table 1}


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