The Phosphate Additives Phosphoric Acid and Sodium Phosphate Lead to Hyperphosphatemia as well as Increased FGF23 and Renal Phosphate Excretion in Healthy Cats

Abstract

Chronic Kidney Disease (CKD) is an increasingly frequent disease in geriatric cats, representing the leading cause of death in this species. Reports about the increasing prevalence of CKD exist also in human medicine. The intake of nutrients, notably phosphorus, can affect renal health. Dietary supply with phosphate can influence concentrations of phosphate and factors of the phosphate homeostasis in blood and urine, possibly causing adverse health effects. Investigating nutritional factors involved in the cause and aggravation of kidney damage in more detail is of high importance not only for feline health. The cat is already successfully used as model for various human diseases which highlights its potential role as translational model for phosphate toxicity in humans. Effects of the food additives H 3 PO 4 and NaH 2 PO 4 on phosphorus homeostasis were investigated in comparison to a control diet. Adding these highly available phosphate additives to the diet of healthy cats for 28 days caused a significant increase in serum phosphate, calcium, and FGF23 as well as in renal phosphorus excretion. Consequently, the use of both phosphate additives in food processing needs to be critically re-evaluated due to the high availability of these sources and therefore their potential adverse health effects. With up to 80 % prevalence, Chronic Kidney Disease (CKD) is one of the most common chronic diseases in geriatric cats [1,2], and represents the leading cause of death in this species [3]. Reports of the increasing prevalence of CKD in the last decades also exist in human medicine [4]. It has been shown in various species, including humans and cats, that the supply of nutrients, notably phosphorus, can affect renal health [5][6][7]. To investigate nutritional factors involved in cause and aggravation of kidney damage in more detail is therefore of high importance not only for feline health. The fact that the cat has been successfully used as a model for human diseases in several studies [8][9][10][11][12] supports its potential role as translational model for human medicine.