Hyperphosphatemia in Chronic kidney diseaseHyperphosphatemia treatment in Chronic kidney disease. CKD (Chronic Kidney disease) is also referred to as chronic renal failure or CRF. CKD is a decreased glomerular filtration rate of less than 60 for a minimum period of 3 months. There is a positive phosphate balance in chronic kidney. There are 2 forms of vitamin D. 25 hydroxyl form of Vitamin D is converted to the active 1,25-dihydroxyvitamin D [1,25(OH)2D] form. This conversion takes place in the kidneys. Kidney regulates phosphorus excretion. Kidney injury makes the ability of  the kidneys to maintain phosphorus homeostasis defective. The elevated phosphate levels signify advance CKD particularly, in stage 4 or 5.

Hyperphosphatemia in Chronic kidney disease is a known cardiovascular risk factor. It has been shown to promote vascular calcification, leading to excess cardiovascular related morbidity in CKD.

In CKD, the kidneys lose their capacity to activate vitamin D and form the 1 , 25 metabolite. Without the activated vitamin D the body will absorb much less quantity of calcium resulting in hypocalcemia, PTH will try to adjust overcompensate for this lowered calcium at the expense of the bone by virtually bleaching out the calcium in the bones to maintain electrolyte balance. This lowered calcium is a stimulus for the parathyroid and results in a secondary hyperparathyroidism. The high levels of parathyroid hormone lead to both calcium and phosphate loss/excretion and resulting in weakening of the bones. Due to the injured kidneys , the excess phosphate which is released as a result of the high levels of parathyroid hormone cant get excreted and builds up.

To address the Hyperphosphatemia treatment in Chronic kidney disease , vitamin d levels are supplemented or activated forms of vitamin D are administered to counter the hypocalcemia leading to the elevated PTH and ultimately causing osteodystrophy.  The vitamin D should not be given alone as vitamin D administration in CKD , alone would lead to increased reabsorption of both calcium and phosphate. Phosphate binders should be given in addition to the vitamin D.

Phosphate binders include Sevelamer, lanthanum, calcium acetate and calcium carbonate. In hypocalcemic hyperphosphatemia , the calcium based phosphate binders  are advised. In hypercalcemic cases, the preferred option is sevelamer or lanthanum.

Our nephrology section has further articles related to kidney disorders. Click on the blue colored nephrology link for further articles.