Bone pain on Dialysis: What you should know and watch out for

I have struggled with bone pain for many years. The worst years were probably 2009-2010 before we finally realised what was causing it and found the solution. That was not the end, though. It kept returning repeatedly and changes in medication helped only for a short while. 

I have not yet found a steady-state where a particular combination and dosage of medicines gives me a permanent solution. My nephrologist says there is no steady-state. We have to keep testing the blood and then change the medication based on the results.

Patients who have been on dialysis for long durations, frequently report bone pain.

The reasons are well known.

Kidneys produce Calcitriol which absorbs Calcium from the food. When kidneys are not functioning, Calcitriol production also stops. This means that Calcium is no longer being absorbed from the body. Calcium is a very important mineral for the body. Apart from forming bones, it is also critical for the functioning of the muscles and nerves and for the clotting of blood.

It is so important that evolution (or God, depending on your religious beliefs) has built a backup control mechanism for regulating Calcium in the body - the Parathyroid Hormone (PTH) which is produced by the Parathyroid Glands. PTH leached Calcium from the bones and releases it into the blood. Bones are the stores of Calcium. Whenever Calcium in the blood becomes low, Calcium needs to move from the bones to the blood.

The Parathyroid Glands act like a thermostat but instead of heat, by Calcium. If the level of Calcium in the blood becomes low, these glands produce more PTH which gets Calcium from the bones to move to the blood. If Calcium levels rise, then PTH production slows down and this leaching of Calcium from the bones reduces.

Now, cut to the fun situation when your kidneys have stopped working. Calcium is not being absorbed from the food because there is little or no Calcitriol. The Calcium level falls. PTH level increases. Calcium keeps getting leached from the bones to compensate. Over years, this results in the bones becoming weak because a lot of Calcium has been removed. This causes bone pain.

Phosphorus also contributes to all this tamasha. Healthy kidneys remove excess Phosphorus from the blood. With the kidneys not working, Phosphorus builds up in the blood. Phosphorus loves Calcium and keeps attaching itself to Calcium, causing even more Calcium to be removed from circulation.

What an unholy mess!

Thankfully, there are solutions:

1. Medicines like Calcitriol, which is an oral capsule that does the same job as natural Calcitriol

2. Phosphate binders which bind the Phosphorus and excrete it out of the body

3. Medicines like Cinacalcet, which act like Calcium and suppress the PTH

4. If all this does not help, doctors sometimes consider surgical removal of a part of the Parathyroid Glands

What you can do:

1. Keep a check on your Calcium and Phosphorus periodically. The product of the Serum Calcium (mg/dL) and Serum Phosphorus (mg/dL) should be less than 55. 

2. Test iPTH (Intact PTH), which is an established blood test for the level of PTH. Test this as per your doctor's advice. Note that the normal range of iPTH in Dialysis Patients differs from that in the healthy population. Ours should be 2 to 9 times the upper limit of the normal range in healthy people.

2. Control intake of foods rich in Phosphorus like milk products, pulses, nuts and foods with preservatives.

3. Take your Phosphate Binders as prescribed.

4. Exercise regularly. We know exercise helps build strength in the bones.

Bone pain can be very frustrating. It is difficult to treat, and even after you have found the right fix, it takes time to go.

It is therefore important for us to speak to our doctor whenever we have any symptoms that we haven't noticed before. Early detection helps to diagnose and treat early minimising the damage.