Researchers in China using spectral computed tomography (CT) characterized the bone changes that occur in hemodialysis patients after undergoing a parathyroidectomy for refractory secondary hyperparathyroidism (SHPT), according to a recent report.

Their analysis showed that calcium concentration increased in cortical bone and decreased in cancellous bone after the surgery.

In a prospective study of 78 male hemodialysis patients, Qiang Ma, MD, of Beijing Friendship Hospital, Capital Medical University , Beijing, China, and colleagues used spectral CT to evaluate the influence of parathyroidectomy (PTX) on calcium concentration in cortical and cancellous bone. The researchers measured calcium concentration in cortical bone in the proximal femur and cancellous bone in the lumbar spine.

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Study participants included 38 men with refractory SHPT who underwent PTX and had parathyroid hormone (PTH) levels below 300 pg/mL after surgery. The other 40 men did not undergo PTX and also had PTH levels below 300 pg/mL. Researchers followed up with patients for 2 years.

In the PTX group, mean cortical bone calcium concentration increased from about 221 to 257 mg/cm3 and cancellous bone calcium concentration decreased from 55 to 61 mg/cm3 from baseline (prior to PTX) to the end of study, the investigators reported online ahead of print in Radiology. Mean serum PTH levels from decreased from 1363 to 101 pg/mL.

In the non-PTX group, mean cortical bone calcium concentration dropped from 296 to 258 mg/cm3 and medullary bone calcium concentration rose from 61 to 63 mg/cm3. Mean serum PTH levels increased from 144 to 181 pg/mL.

“Bone abnormalities caused by chronic kidney disease may result in high-turnover bone disease, which appears as increasing calcium concentration in cancellous bone and decreasing calcium concentration in the cortex,” Dr Ma and colleagues concluded. “A low PTH state after PTX, which may manifest as decreasing calcium concentration in cancellous bone and increasing calcium concentration in the cortex, could occur after PTX. Spectral CT could be a useful tool for analyzing bone metabolism in patients undergoing dialysis.”

The PTX and non-PTX patients were similar with respect to age (mean 55.7 and 56.7 years, respectively), body mass index (22.73 and 22.23 kg/m2), and dialysis duration (124.9 and 107.3 months).

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