As you know, I have been on dialysis for the last twenty and half years. I have seen many co-morbidities during this period but none so complex and difficult to get a handle on as Mineral and Bone Disorders (MBDs). This problem has confounded many senior nephrologists as well and a steady-state s very difficult to achieve.
To address MBDs you need to balance the levels of Calcium, Phosphorus, Parathyroid Hormone and Vitamin D. Calcium is a very important element and is essential for the proper functioning of our body like the muscles, nerves and bones. So evolution or God, depending on which side of the divide you are on, created the Parathyroid glands that generate Parathyroid Hormone and the sole function of this hormone is to regulate Calcium in the blood. When this gland senses that the level of Calcium is going down in the blood, it releases more of this hormone which gets Calcium from the Calcium stores of the body - the bones, and releases it into the blood. The opposite happens when the level of Calcium in the blood becomes high.
Vitamin D, on the other hand ensures proper absorption of the Calcium that is a part of the food we take.
The trouble with kidney disease is that the functioning of the Parathyroid glands is affected. This results in a condition called Secondary Hypeparathyroidism (as opposed to Primary Hyperparathyroidism, a condition where the glands are affected inherently) which releases excess Parathyroid hormone and this causes the Calcium levels in the blood to go too high. Over a period of time, this results in bone loss as the hormone is leaching too much Calcium from the bones.
The solution to treat this problem is to take a class of drugs known as calcimemetics like calcitriol which work to reduce the amount of the Partathyroid hormone in the body. However, the danger of this drug is that it can at times reduce the level of the hormone too much and this condition called Low turnover bone disease can be even more dangerous than what it is trying to treat.
Add Phosphorus to the mix and you have a cocktail heady enough to get even the most experienced nephrologist, not to mention, his or her patients left feeling tizzy.
I have been struggling with this condition for many years now. Every month I need to test my Calcium, Phosphorus and iPTH to decide what combination of drugs I am going to be on that month. There never is a steady state. We have tried every combination in the book and out of it but have yet been unable to get our heads around this conundrum of MBDs.