Thesis:

The study of normal calcium-creatinine ratio of children urine specimens in the Sabzevar province

Calcium is known as a necessary biochemical agent to tense muscles and also transfer nerve data in body. Serum calcium indicates Vitamin D concentration and parathyroid hormone functional level. Also, the biochemical agent is a major agent for formatting kidney calcium stones which is resulted by increased kidney calcium concentration. Urinary calcium excretion is used to evaluate various clinical conditions such as idiopathic hypercalciuria. Idiopathic hypercalciuria indicates increasing urinary calcium concentration. However, urinary calcium excretion of less than 200 mg/L is considered normal. The ratio of creatinine to urinary calcium is different for defining hypercalciuria in different age groups and according to region. The disease associates with other diseases such as hematuria, urinary disorders and decreased bone mineral density in children. Hypercalciuria is defined as daily urine excretion of more than 4 mg per kilogram of body weight in children. Based on this, it seems that obese children will have more calcium excretion compared to thin children. The ratio of urinary creatinine to calcium is a reliable indicator for the diagnosis of hypercalciuria. The etiology of hypercalciuria is complex and involves interactions between the gastrointestinal tract, bone, and kidney, mostly influenced by hormones such as parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D3. This ratio is different in geographical areas and should be defined separately in each geographical area. Physiological hypercalciuria is related to excessive intake of sodium, calcium or protein in the diet. This study was conducted with the aim of determining the normal values of the random ratio of calcium to creatinine according to age, gender and ethnicity and to determine the relationship between the ratio of calcium to creatinine in healthy primary school students of Sabzevar city, in the east of Iran. Methodology:This study was conducted in 1402 in the Sabzevar province, for children aged 7 to 12 years. In this study, laboratory containers in a sterile package (for urine collection), pH strip (urine pH measurement), bacterial loop, culture medium plates, McConkey Agar bacterial culture medium, incubator (incubating bacteria), autoclave (sterile) culture medium) was used. Study subjects were classified based on age and gender. Also, the studied children were divided into three groups: 1) control, 2) the group of patients without kidney stones and 3) the group of patients with kidney stones. All fasting morning urine samples were examined in terms of macroscopic and microbial characteristics. The ratio of calcium to creatinine in these samples was checked by spectrophotometric method and the results of the data were analyzed statistically. Results and finding: In this study, 245 samples (63.8 percent) were collected from boys and 139 samples (36.2 percent) were collected from girls among 384 urine samples that were taken in 1402 in Sabzevar city. Based on age, 197 samples (51.3%) were collected in the age group of 10 to 12 years and 187 samples (49.7%) were collected in the age group of 7 to 10 years. Bacterial cultures of all urine samples were negative, which means that there were no bacterial urinary infections in the people. In this study, by examining the ratio of calcium to creatinine, it was found that the urinary excretion ratio of calcium to creatinine was below 0.1 in 89 samples (23.2 percent), 121 samples (31.5 percent) were between 0.1 to 0.20 and 174 The higher sample (45.3%) was equal to 0.21 mg per ml. Discussion: Idiopathic hypercalciuria is the most common cause of calcium stones and may be transient in childhood. In infants and young children, the ratio of urinary calcium to creatinine is used for diagnosis. However, this ratio is strongly age-dependent and decreases significantly during the first year of life. Differences in gender predominance in pediatric kidney stones may be explained by variations in the inclusion criteria used in the studies and the proportion of boys and girls in the populations from which the study samples were drawn. In the present study, male patients were about 63.8% and girls were 36.2%. In the present study, despite the increase in the number of boys compared to girls, there was no significant difference between gender and hypercalciuria. The absence of a significant difference in the ratio of calcium to creatinine in the present study can be attributed to the sampling method and the statistical population investigated in this study. Despite the presence of hypercalciuria in boys and girls, there were no urinary infections of bacterial origin. Meanwhile, in some studies, symptoms such as kidney pain and heartburn, abdominal pain, presence of blood in urine, and positive urine culture in terms of bacterial infection were seen among hypercalciuria patients.

Keywords: Calcium, Creatinine, urine specimens, Idiopathic hypercalciuria