Kidney Diseases and Muscle Cramps

Some kidney disease patients may experience muscle cramps and this is mainly due to hypocalcaemia (low blood calcium level). And why kidney disease patients have muscle cramps and how to prevent and deal with it?

There are several reasons for low calcium in blood:

1. Kidney disease patients usually have strict diet restrictions to reduce burdens to the impaired kidney and preserving kidney functions, as a result, patients will have shortage of vitamin D. Besides, there will be metabolic disorder of vitamin D. Chronic kidney failure patients usually have inadequate 1-hydroxylase and can not synthesize active vitamin D3 which has strong biological activities and can promote the absorption of calcium in the gastrointestinal tracts. The decrease of vitamin D3 will reduce absorption of calcium.

2. Hyperphosphatemia. Due to the decrease of glomerular filtration rate, the discharge of phosphorus will be decreased and there will be phosphate ion retention in the blood and cause phosphorus level to increase which will cause lowered calcium in the blood because the product of serum calcium and phosphorus is relatively constant.

Light hypocalcaemia can cause stinging pain around the mouth and in the limbs without obvious muscle cramp and moderate hypocalcaemia can cause systemic skeletal muscle and smooth muscle cramps. In case of metabolic acidosis, the free calcium is in large proportion due to lowered PH value though the total serum calcium is low. This reduces the irritability of the nerves and muscles and patients can have no muscle cramps despite hypocalcaemia. However patients usually will have muscle cramps after the metabolic acidosis is rectified, therefore at the same time of treating acidosis, proper amount of calcium should be supplied.

In treating muscle cramps in kidney diseases, proper preventions are the best treatment. Patients should try to avoid over-tiredness, cold and strenuous activities and have proper supplement of calcium.