Hyperparathyroidism, hypophosphatemia & hypercalcemia
Assessing the Clinical and Laboratory Parameters
This scenario is unusual because of the hypophosphatemia – otherwise the pattern is consistent with failing medical management of secondary hyperparathyroidism
Less than 1% of all patients are in this category.
Dialysis Prescription
Dialysis Prescription
Reduction in the dialysate calcium by 0.25-0.50 mmol/L (0.50 – 1.0 mEq/L) may alleviate the hypercalcemia, but will also exacerbate the secondary hyperparathyroidism
Phosphate and Calcium Management
Phosphate and Calcium Management
Therapeutic avenues;
- If managed with calcium based binders, switch to non-calcium based alternatives.
- If managed solely with calcium based binder, a reduced dose may allow normalization of serum phosphate levels, and potential to increase dose of vitamin D analogue (see below)
PTH Management
PTH Management
Vitamin D Sterols
If vitamin D sterols are in use, the PTH is high despite them and hypercalcemia is present. Therapeutic avenues;
- Most patients will not tolerate starting active vitamin D analogues without further increases in hypercalcemia
- If currently taking active vitamin D analogues, consider a “less calcemic” regimen, i.e, night-time oral dosing on alternate days, switching from oral to intravenous dosing, switching to different analogues (e.g.doxercalciferol)
Calcimimetics
This is the therapy of choice in this situation, with the potential to correct the hyperparathyroidism and normalize serum calcium.
Neither the CSN, nor the KDIGO guidelines comment on the specific role of calcimimetics in this situation. No specific evidence relates to the role of this agent in preventing a need for parathyoidectomy.
Block et al published the Phase III randomised controlled trial of cinecalcet in patients with severe secondary hyperparathyroidsm. (Cinacalcet for Secondary Hyperparathyroidism in Patients Receiving Hemodialysis, New Engl.J.Med 350:1516,2004)
Other Options or Controversies in Management
Other Options or Controversies in Management
Parathyroidectomy
Hypercalcemic patients with very high serum (intact)PTH levels (e.g. > 60 pmol/L) often fail medical therapy (outlined above), and require parathyroidectomy
Suggested Guidelines;
CSN
8. Parathyroidectomy should be considered for those patients who have failed standard treatments and have persistently elevated PTH levels with systemic complications. (Grade D, opinion)
KDIGO
4.2.5 In patients with CKD stages 3–5D with severe hyperparathyroidism (HPT) who fail to respond to medical/pharmacological therapy, we suggest parathyroidectomy (2B).
Elder has reviewed this topic (Elder GJ, Parathyroidectomy in the calcimimetic era, Nephrology 2005). Parathyroidectomy may be the treatment of choice when averaged serum intact-PTH levels are consistently above 85-95 pmol/L despite optimal therapy.
