Consult rounds: Electrolyte abnormalities associated with Primary hyperparathyroidism

Classically, we are notified to see a patient with hypercalcemia and one of the diagnosis that is made is primary hyperparathyroidism (PHPT). Due to the elevated PTH, what other electrolytes can go out of order?

1.       Hypophosphatemia:  Elevated PTH levels tend to lead to phosphate wasting in the urine.  Proximal tubular absorption of phosphorus( Na –Phos co transporter)  is blocked leading to renal wasting.

2.       Hypomagnesemia: This one is interesting as hypercalcemia would lead to decrease magnesium absorption via Ca-Sensing receptor in the TAL but PTH would increase magnesium absorption.  But net effect usually is “ hypercalcemia” wins leading to mg wasting as well. This in turn might lead to hypokalemia as well.

3.       Metabolic acidosis: Elevated PTH levels lead to decrease proximal bicarbonate absorption and leading to mild metabolic acidosis. This is usually seen when you have AKI as well compounding this problem.

   

NKF 2011 Live Blogging: Integrating the treatment of secondary hyperparathyroidism in ESRD

Integrating the treatment of secondary hyperparathyroidism in ESRD 
Speaker Dr. Malluche 
Blogger: Dr.Azzour Hazzan

Some points from the lecture:1.There are 5 different pth assays assays
2. Have different specificity and sensitivity but the trend is telling and should be trusted. 
3.Further using ratio of cap and cip may help (cap is the activating protein within the pth peptide)
4. Using pth you can only screen for high turn over, not diagnose it.
5. Bone volume is also important. 
6. Dexa is unreliable and in some cases can give falsely high readings( especially vertebral bones). The hip readings are good
7. Higher bone volume correlates  with less calcification in the coronary arteries  and vice versa. And that is true with any age. 
8. More low turn over with whites along with low volumes 
9. More porosis with blacks and high turn over