Desired PTH, hyperphosphatemia and hypercalcemia

Patient Scenario: Desired PTH, hyperphosphatemia and hypercalcemia

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Assessing the Clinical and Laboratory Parameters

Phosphate control is suboptimal in this patient. Assess dietary intake, binders and timing of binders with meals.  

Assess use of vitamin D and Calcimimetics. The PTH level is at the target range, which may be due to the current use of vitamin D sterols in an effort to control hyperparathyroidism.  The vitamin D sterol may be increasing both the calcium and the phosphate absorption.  It is likely that the hypercalcemia is also contributing to the current PTH level.

It is unusual to see hyperphosphatemia and hypercalcemia in a patient receiving calcimimetics

Approximately 4% of all patients are in this category.


Therapeutic Options:


{tab=Dialysis Prescription}

Dialysis Prescription

Nocturnal dialysis may be a good option for this patient as this modality has been shown to lower phosphorus. Lowering the dialysis calcium bath could be considered, but this would not be expected to improve phosphate control, and may provide a stimulus to increase PTH.

 

{tab=Phosphate and Calcium Management}

Phosphate and Calcium Management

Ongoing counseling about phosphate in the diet and the timing of binders with respect to meals is required.  If the patient is receiving a vitamin D sterol, the dose should be reduced. The dose of calcium containing phosphate binder in this patient needs to be reassessed given the presence of both hypercalcemia and hyperphosphatemia. Unless vitamin D sterols are being used, the dose of calcium binder would need to be significantly reduced or withdrawn depending on the degree of hypercalcemia.  This would be expected to raise the phosphate and the PTH, thus a non-calcium containing binder would have to be added in for phosphate control. Rescue aluminum could be used for severe hyperphosphatemia, but alternative non calcium, non aluminum binder could be used for less severe hyperphosphatemia.

 

{tab=PTH Management}

PTH Management

A reduction or discontinuation of the vitamin D sterol dose is required, which may lower both the calcium and the phosphate, but cause the PTH level to rise. If the PTH rises above the target range the options are to reinstitute or increase the dose of the vitamin D sterol if the calcium and phosphorous levels are better or to use a calcimimetic if assess is available.

 

{tab=Other Options of Controversies in Management}

Other Options of Controversies in Management

If the PTH rises above the target range and vitamin D sterol use causes increase in both calcium and phosphorous the options are calcimimetic or parathyroidectomy (PTx). Rates of PTx were in decline several years ago, but seem to be increasing. When comparing calcimimetic to surgery the cost of the surgery is less, however, the rate of future increased PTH can be as high as 37 % due to additional glands or cells in the thymus and there is the risk of surgery. A retrospective cohort study by Kestenbaum found an increase risk in death the first 3 months after PTx but a decreased mortality after 6 months. In diabetics, the increased mortality was seen for 12 months.

 

 

{tab=Suggested References}
Suggested References

1. Kestenbaum B, Andress DL, Schwartz SM, et al. Survival following parathyroidectomy among United States dialysis patients. Kidney Int 2004;66:2010-6

2. Hindié E, Zanotti-Fregonara P, Just PA, Sarfati E, Mellière D, Toubert ME, Moretti JL, Jeanguillaume C, Keller I, Ureña-Torres P. Parathyroid scintigraphy findings in chronic kidney disease patients with recurrent hyperparathyroidism Eur J Nucl Med Mol Imaging. 2009 Nov 28. [Epub ahead of print]

3. Low TH, Clark J, Gao K, Eris J, Shannon K, O'Brien C. Outcome of parathyroidectomy for patients with renal disease and hyperparathyroidism: predictors for recurrent hyperparathyroidism, ANZ J Surg. 2009 May;79(5):378-82.

 

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