High Post-op iPTH Linked With Increased Mortality in SHPT

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The risk of death more than tripled with iPTH levels above 600 pg/mL at 1 week after surgery.
The risk of death more than tripled with iPTH levels above 600 pg/mL at 1 week after surgery.

For patients with refractory secondary hyperparathyroidism (SHPT), the best parathyroidectomy (PTx) procedure and optimal post-op parathyroid hormone levels for survival have yet to be determined. A new Chinese study suggests that 1-week post-op intact parathyroid hormone (iPTH) levels above 600 pg/mL are associated with higher risks of death.

Qiu Ping Xi, MD, of China-Japan Friendship Hospital in Beijing, and colleagues examined all-cause mortality among 525 dialysis patients with refractory SHPT (pre-operative serum iPTH above 800 pg/mL) along with hypercalcemia, hyperphosphatemia, or calcium × phosphorus product above 70 mg2/dL2. Patients underwent total PTx, subtotal PTx, or total PTx with autotransplantation in standardized procedures at 5 hospitals.

Of 404 patients, 8.91% died during 11 years of follow-up. The investigators examined all-cause mortality by quartiles of 1-week post-op iPTH: group A 20 pg/mL or less; group B 21 to 150 pg/mL; group C 151 to 600 pg/mL; and group D above 600 pg/mL. The death rates were 8.29%, 3.54%, 10.91%, and 29.03% for groups A, B, C, and D, respectively, the investigators reported online in BioMed Research International.

Compared with group A (reference), group B had a 43% lower risk of death, whereas groups C and D had a 1.43- and 3.45-fold increased risk of death, respectively.

All-cause mortality appeared to demonstrate a U-shaped relationship with post-op iPTH. Previous studies have found greater mortality with very low or high PTH, but depending on the population, the iPTH cutoffs varied.

“Attention needs to be paid not only to high PTH but also to low PTH since both of them might influence the quality of life of patients,” Dr Qiu and colleagues wrote.

The study was underpowered to detect significant differences, so the investigators are increasing the sample size for a future study.

They further noted that just 0.7% of studied patients had diabetic nephropathy as the underlying cause of CKD, suggesting that high glucose may suppress PTH secretion.

Reference

1. Ping Xi Q, Sheng Xie X, Zhang L, et al. Impact of Different Levels of iPTH on All-Cause Mortality in Dialysis Patients with Secondary Hyperparathyroidism after Parathyroidectomy. BioMed Res Intl. doi: 10.1155/2017/6934706

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