A 31-year-old female patient reported severe pain in the right hand, left forearm, right knee, right hip, and lower back following a fall which sustained for three days. She had reported a history of end-stage renal disease (ESRD) and was on maintenance haemodialysis. Medical records revealed that she had poor compliance with her diet, medications, and dialysis treatments. Laboratory values were significant for marked elevation in serum parathyroid hormone level (1735 pg/mL), as well as hyperphosphatemia and normal serum calcium levels.
These symptoms are most consistent with which of the following disease?
In
chronic kidney disease (CKD) patients, the levels of parathyroid hormone (PTH)
are progressively increased. Several observational studies determined an
association between PTH levels at extremes and mortality in CKD patients. It is
difficult to observe skeletal symptoms of secondary hyperparathyroidism with
early detection and treatment of CKD.
Patient with end-stage renal disease developed severe
hyperphosphatemia and hyperparathyroidism. High-dose phosphate binder and a
calcimimetic agent were initiated to manage hyperphosphatemia and hyperparathyroidism.
The patient reported a history of hypertension,
diabetes, and congestive heart failure and end-stage renal disease, for which
she was receiving maintenance hemodialysis for the past 15 years. She also had
a history of chronic leg pain and disabling peripheral neuropathy which made
her wheelchair-bound. The femoral fracture was also reported about a year ago
but was managed with the conservative treatment approach.
Physical examination showed a blood pressure of
153/81 mm Hg and pulse rate of 101 bpm. Tenderness and moderate swelling over
the tip of the right index finger and right distal femur was also reported. She
found difficulty in the motion of the right knee due to pain. The patient did
not report any distal neurovascular deformity in the extremities.
The
patient was administered with medications including aspirin (81 mg/day),
lisinopril (40 mg/day), carvedilol (25 mg twice a day), sevelamer carbonate
(800 mg thrice a day with meals), and insulin regimen. The patient did not show
compliance with diet, medications and hemodialysis.
The
fractures were treated with non-operative treatment due to severe
hyperparathyroidism and poor baseline functional status. The patient was not
comfortable in undergoing surgical parathyroidectomy. A high-dose phosphate
binder (sevelamer carbonate) and also an oral calcimimetic (cinacalcet) were
started for management of hyperparathyroidism and hyperphosphatemia.
The patients with advanced kidney disease show a decrease in the phosphorus clearance, which in turn decreases the glomerular filtration rate (GFR). Subclinical and postprandial hyperphosphatemia has been observed even in patients with a GFR of greater than 30 mL/min, which may be a significant cause of secondary hyperparathyroidism. Bone resorption (increase in serum concentration of calcium and phosphorous) is caused by osteoclasts which are stimulated by PTH. Additionally, PTH also increases intestinal phosphorus and calcium absorption by stimulating the production of 1,25-dihydroxy vitamin D. Research has reported the negative effect of calcium on the parathyroid hormone through the calcium-sensing receptors. Cinacalcet works mainly by activating calcium-sensing receptors.
The
most critical step in the management of hyperthyroidism due to kidney disease
starts with optimizing calcium and serum phosphate levels. High PTH levels can
be effectively reduced by supplementing calcitriol. But, careful monitoring is
required as calcitriol may augment calcium and phosphate absorption from the
gut, thereby increasing calcium-phosphate product.
Previous research studies have shown that the severity of secondary hyperparathyroidism even in ESRD patients receiving dialysis is attributed to 25-hydroxyvitamin D levels below 15ng/mL. The addition of calcimimetic drug should be considered in patients with persistently elevated PTH levels despite optimising serum phosphate and calcium levels. The patients with serum calcium lower than 8.4 mg/dL should not receive cinacalcet as it can cause severe hypocalcaemia.
In this case, cinacalcet addition was considered as the patient had serum PTH levels of >1000pg/mL, and the chances of improvement with hyperphosphatemia control alone were low. Surgical parathyroidectomy should be considered if the patients have markedly elevated PTH levels and have unmanageable signs and symptoms. Research has suggested the use of parathyroidectomy in reversing bone resorption and regressing brown tumors completely.
In
the present case, all-cause or cardiovascular mortality failed to improve with
the use of cinacalcet. Still, the use of cinacalcet may diminish the
requirement of parathyroidectomy in ESRD patients.
Patients with chronic kidney disease, especially
those who are on dialysis, are at higher risk of bone fractures and secondary
hyperparathyroidism.
Reduction in active vitamin D production,
accumulation of phosphate and hypocalcemia may act as stimuli for increased
secretion of PTH. Therefore, laboratory measures should be monitored
periodically and optimized early in the course of CKD.
Adherence to therapy and appropriate patient
education plays a prominent role in the management of bone-eating disease.
SAGE Open Med Case Rep. 2017; 5: 2050313X17744983.
Bone-eating kidney disease
Abhilash Koratala et al.
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