Vitamin D in Chronic Kidney Disease and Dialysis Patients

Abstract

Vitamin D deficiency (<20 ng/mL) and insufficiency (20–29 ng/mL) are common among patients with chronic kidney disease (CKD) or undergoing dialysis. In addition to nutritional and sunlight exposure deficits, factors that affect vitamin D deficiency include race, sex, age, obesity and impaired vitamin D synthesis and metabolism. Serum 1,25(OH)2D levels also decrease progressively because of 25(OH)D deficiency, together with impaired availability of 25(OH)D by renal proximal tubular cells, high fibroblast growth factor (FGF)-23 and decreased functional renal tissue. As in the general population, this condition is associated with increased morbidity and poor outcomes. Together with the progressive decline of serum calcitriol, vitamin D deficiency leads to secondary hyperparathyroidism (SHPT) and its complications, tertiary hyperparathyroidism and hypercalcemia, which require surgical parathyroidectomy or calcimimetics. Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease Improving Global Outcomes (KDIGO) experts have recognized that vitamin D insufficiency and deficiency should be avoided in CKD and dialysis patients by using supplementation to prevent SHPT. Many vitamin D supplementation regimens using either ergocalciferol or cholecalciferol daily, weekly or monthly have been reported. The benefit of native vitamin D supplementation remains debatable because observational studies suggest that vitamin D receptor activator (VDRA) use is associated with better outcomes and it is more efficient for decreasing the serum parathormone (PTH) levels. Vitamin D has pleiotropic effects on the immune, cardiovascular and neurological systems and on antineoplastic activity. Extra-renal organs possess the enzymatic capacity to convert 25(OH)D to 1,25(OH)2D. Despite many unanswered questions, much data support vitamin D use in renal patients. This article emphasizes the role of native vitamin D replacement during all-phases of CKD together with VDRA when SHPT persists.

Comparison of laboratory and imaging methods associated with bone metabolism in patients with or without renal failure under the age of 45 years with elevated parathyroid hormone levels

“…Vitamin D deficiency was shown to be more prevalent even in the early stages of CKD in comparison to the general population [20]. In contrast to the expected, 25-OH-D levels were statistically significantly elevated in our patients with CKD probably due to the replacement therapies.…”

Estimation of Serum Vitamin D, Calcium and Phosphorus in Chronic Kidney Disease

“…Corrected calcium was calculated by using the equation-Corrected Calcium = measured Ca + 0.8 (4.0 -albumin). 5 According to laboratory parameters the CKD patients were grouped in to vitamin D sufficient (>30 ng/ml), insufficient (20 to 30 ng/ml) and deficient (<20 ng/ml) 6 and corrected calcium < 8.5 mg% and >10.5 mg % as hypocalcemia and hypercalcemia respectively, and serum phosphorus <2.5 mg% and >4.5 mg% as hypophosphatemia & hyperphosphatemia respectively. 15 Statistical analysis: Data analysis was performed by SPSS soft-ware package 19.0.…”

“…2 Initially, transient retention of phosphorus, due to failing kidney, results decreased activity of renal 1-a hydroxylase in proximal tubule with decreased calcitriol (1,25 OH2 vitamin D) synthesis there by probably due to its prevalence in general population or due to different factors related to CKD has predisposed low vitamin D level with its greater incidence in CKD compared to healthy control. [6][7][8] Apart from calcitrophic effects, vitamin D has multiple beneficial effects in the body and h y p o v i t a m i n o s i s D r e s u l t s i n i n c r e a s e d cardiovascular mortality in CKD as vitamin D supplementation in these patients had decreased cardiovascular risk with increased survival. 6,9,10 Prevalence of hypovitaminosis D in 73.7% healthy Nepalese population and 89.1% patients with different health related problem were reported.…”

“…[6][7][8] Apart from calcitrophic effects, vitamin D has multiple beneficial effects in the body and h y p o v i t a m i n o s i s D r e s u l t s i n i n c r e a s e d cardiovascular mortality in CKD as vitamin D supplementation in these patients had decreased cardiovascular risk with increased survival. 6,9,10 Prevalence of hypovitaminosis D in 73.7% healthy Nepalese population and 89.1% patients with different health related problem were reported. 11, 12 But there is no reported study on status of vitamin D level and its calcitrophic and non calcitrophic effects in Nepalese CKD patients.…”

Vitamin D for Depression with a Seasonal Pattern: an Effective Treatment Strategy

“…84 Vitamin D insufficiency and deficiency is prevalent in patients with chronic kidney disease and dialysis patients. 85,86 Low level of Vitamin D causes an increase in serum parathyroid hormone (PTH) levels causing primary hyperparathyroidism which in turn is associated with symptoms of depressive disorder. 87 Therefore, studies indicate that low level of vitamin D is associated with chronic diseases and depression.…”