Following treatment for 8, 12, or 24 months, an improvement of bone biopsy features was noted in the vitamin D-treated patients. If the dosage is below a 0. Patients with CKD or those who are dialysis-dependent are much more likely to have low levels of 25 OH D in comparison to those with no kidney disease for several reasons:. However, a bone biopsy should be considered in patients with kidney failure Stage 5 who have:.
This leads to reduced intestinal absorption of calcium thereby contributing to hypocalcemia and impaired suppression of the parathyroid gene that initiates the synthesis of PTH.
Thus, the newer vitamin D analogs have largely obtained FDA approval for use in the control of intact PTH and do not have adequate data to document their effect on bone histology.
Studies of 25 OH D levels in patients with CKD and varying degrees of decreased kidney function from five reports were reviewed. There are many of these sterols available and others are being developed.
Newer assays which are more specific for the PTH molecule have been developed, and are becoming available, but warrant further study of their clinical utility. Many of the studies cited above with calcitriol and alfacalcidol that originated before lacked parallel control groups,, and the assays for PTH were variable and some involved PTH fragmentsthat are cleared by the kidney; thus, comparison with the current trials that utilize so-called "intact PTH" is not possible.
Clearly, hyperparathyroidism is a frequent complication of CKD which requires monitoring and therapy. Large studies that evaluate fracture rates should include data on previous vitamin D therapy in an effort to identify whether vitamin D treatment can modify the high incidence of fractures noted in end-stage kidney disease patients.
Treatment with active vitamin D sterols can also markedly lower serum levels of intact PTH and reduce bone formation strikingly; this can produce a condition with low bone turnover, termed adynamic bone disease. Also, these abnormalities were common in the CKD patients recruited only on the basis of their impaired kidney function reduced GFR or elevated serum creatinine levels with the degree of elevation of pretreatment levels of intact PTH totally unknown. However, comparisons of newer vitamin D sterols with calcitriol, alfacalcidol, or even ergocalciferol, at 50, IU monthly, would be ideal.
Some, however, fail these measures and therefore, surgical ablation becomes an option which can effectively control the overactivity of the parathyroid, although recurrence rates are high.
KDOQI Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease
However, in other studies, enhanced growth velocity was not demonstrated on long-term follow-up and further studies have not shown that calcitriol consistently improves linear growth in children with CKD Stages For these reasons, serum levels of calcium, phosphorus, and PTH must be monitored during vitamin D therapy, and vitamin D therapy adjusted accordingly Algorithm 3Algorithm 4and Algorithm 5.
Serum levels of hydroxyvitamin D not the levels of 1,dihydroxyvitamin D are the measure of body stores of vitamin D. The plasma PTH should be measured monthly for at least 3 months and then every 3 months once target levels of PTH are achieved. Two trials compared daily oral treatment with thrice weekly intravenous treatment; in the trial that studied patients with the highest pretreatment intact PTH levels, the oral "group" was a combination of one group randomly assigned to intermittent treatment and a second group assigned to daily therapy.
Treatment with vitamin D should not be undertaken or continued if serum phosphorus levels exceed 6. The therapeutic approach to bone disease in CKD is based on its specific type. Accordingly, some patients require surgical parathyroidectomy to correct the problem.
In dialysis patients who have not received vitamin D, or those who have received daily oral calcitriol in doses lower than 0. Treatment with vitamin D should not be undertaken or continued if serum phosphorus levels exceed 6. Over the last decade, the 1 st PTH-IMA proved to be a reasonably reliable predictor of the different subtypes of renal osteodystrophy and it performed well in assessing the therapeutic response to active vitamin D sterols in patients with renal failure.
The available evidence is obtained from short-term studies and on a relatively small number of patients.