Introduction: The prevalence of nephrolithiasis in Chronic Kidney Disease (CKD) is 5%-10%. To better understand the relationship between thyroid function and nephrolithiasis in the CKD population, we conducted a retrospective study with the main objective to identify the prevalence of nephrolithiasis in CKD and explore the relationship between TSH hormone level and nephrolithiasis.
Methods: A retrospective cohort study was conducted in a community nephrology clinic in Quebec, Canada that included clinical and demographic data collection in an electronic format. The clinical information collected was from April 1, 2015 until December 30, 2019. The outcome of interest was the prevalence of nephrolithiasis, and the exposure variable of TSH level greater than 2.22 μIU/l was analysed by applying unconditional and adjusted generalized linear and logistic regression models.
Findings: The 310 charts were reviewed. The subjects had a median age of 73 years (IQR (interquartile range) 29-99), 58.3% was male, 12.8% had a diagnosis of hypothyroidism and a diagnosis of diabetes mellitus was made in 43.3%. The overall prevalence of nephrolithiasis 10.2% and was 9.4%, 14%, 6%, and 4.4% within the CKD groups combined, Grade 1 and 2,3,4 and 5 respectively. When certain generalized linear regression models were applied, an adjusted odds ratio of 2.38 (CI 95%: 1.08-5.27) was calculated for a TSH level>2.22 μIU/L (Q2), for the presence of nephrolithiasis on baseline CT scan of the abdomen.
Discussion: Our study shows a significant prevalence of nephrolithiasis in CKD, with a higher proportion of kidney stones in the early stages of the renal disease. TSH levels above 2 uIU/L have more than a two-fold higher risk of forming kidney stones. Further studies that address the target thyroxine level to resolve kidney stone formation will be important.