Extra vitamin D and less salt intake best option for patients with chronic kidney disease

Vitamin D deficiency can contribute to kidney damage. This is particularly true for patients who consume much salt, disrupting the hormone system known as the RAAS. A combined treatment involving restricting salt intake and giving active vitamin D supplements seems to benefit patient with chronic kidney disease who continue to excrete urinary proteins despite receiving the standard therapy. These are the results of research carried out by Charlotte Keyzer of the University Medical Center Groningen. An intervention involving combined treatment of both the RAAS and the mineral metabolism slows down deterioration in the kidney function and reduces the risk of cardiovascular disease. Keyzer will be defending her PhD thesis at the University of Groningen on 16 November.

Chronic kidney damage is a growing problem that affects 8-16% of the global population. If it leads to kidney failure, patients are forced to rely on dialysis or a kidney transplant. Chronic kidney damage involves the disruption of two of the body’s important regulation systems: the renin-angiotensin-aldosterone system (RAAS), which causes the body to retain fluid and the blood pressure to rise, and mineral metabolism, which causes arteriosclerosis and bone disease. The usual treatment for chronic kidney disease focuses on regulating the RAAS by means of drugs, which lower the blood pressure and stop the damaged kidneys from excreting protein. However, this treatment is not always sufficiently effective and many patients develop seriously impaired kidney function and a high risk of cardiovascular disease. In her thesis, Charlotte Keyzer explores whether combining an intervention in the RAAS and regulating the mineral metabolism could lead to better treatment for kidney patients.

Vitamin D deficiency

Keyzer’s research shows that a vitamin D deficiency is more likely to lead to kidney damage, particularly in patients who use a lot of salt and subsequently have a more seriously disrupted RAAS. Her study also showed that patients with kidney damage who had vitamin D deficiency had a higher risk of dying. Keyzer then carried out a national clinical trial studying the effects of a combined intervention whereby salt intake was restricted and active vitamin D supplements were given. Her conclusion is that this combination forms a good complementary treatment for patients with chronic kidney damage, who continue to excrete proteins despite the standard treatment using RAAS inhibitors. It was the most effective way of reducing the amount of protein excreted in the urine, which is indicative of prognosis for kidney and cardiovascular outcomes.

Vascular calcification

Vascular calcification increases the risk of cardiovascular disease in patients with kidney damage. Advancing vascular calcification is common among patients with kidney damage. A new test recently developed identifies calcification features in the blood; it gives the sum total of the factors that stimulate and the factors that inhibit vascular calcification. In order to improve treatments for vascular calcification, Keyzer identified various factors that play an important part in the process of vascular calcification. Her research shows that elevated levels of phosphate and the parathyroid gland hormone PTH, combined with a shortage of magnesium and vitamin K can stimulate vascular calcification. This is a good starting point for research into new treatments to prevent vascular calcification and subsequently reduce the risk of cardiovascular disease.

Comprehensive approach

Keyzer thinks that a comprehensive approach using drugs and a special diet that works on both the RAAS hormone system and the mineral metabolism would improve treatments offered to patients with kidney disease in terms of preventing further deterioration of the kidney function and reducing cardiovascular disease.

Curriculum Vitae

C.A. Keyzer (Eindhoven, 1987) studied Medicine at the University of Groningen. She conducted her research in the department of Nephrology at the UMCG. Her thesis is entitled: ‘Clinical implications of the cross-talk between renin-angiotensin-aldosterone system and vitamin D-FGF23-klotho axis’. Keyzer is currently training to become a specialist in internal medicine at the Ziekenhuisgroep Twente in Almelo.

Source: press release UMCG, tel. +3150-361 22 00