Naohiko Kato

The Negative Ca2+ Balance Is Involved in the Stimulation of PTH Secretion

The low calcium (Ca2+) dialysate have been developed to diminish the risk of hypercalcemia with the administration of active vitamin D and Ca2+ carbonate as phosphate binder. Today, increasing numbers of hemodialysis (HD) patients have been on the low Ca2+ dialysate (Ca2+ = 2.5 mEq/l). However, the clinical consequences of a negative calcium net-balance which may be induced by the use of low Ca dialysate are not well evaluated. In the present study, we explored the effects of low Ca2+ dialysate on the calcium balance and the PTH secretion. Eighty one chronic HD patients (male/female: 47/34; mean age: 60.2 ± 1.5 years; mean HD periods: 11.1 ± 0.8 years) who had been dialyzed with 3.0 mEq/l Ca2+ dialysate were studied. All patients were transferred to the low Ca dialysate, which actually brought about a negative net-balance in Ca (mean: –94.5 mg) and an increase in serum intact PTH levels (mean: +23.7%: p = 0.03) during a single HD session. However, no changes in serum ionized Ca2+ were found in spite of negative Ca2+ balance. One month after change to the low Ca2+ dialysate (total 12 sessions in each case), serum intact PTH levels increased significantly (186.7 ± 19.5 vs. 216.2 ± 21.9 pg/ml: p = 0.01) in spite of the fact that no changes were found in serum ionized Ca2+, Pi and Mg. This result indicates that the negative Ca2+ balance during low-Ca2+ hemodialysis-stimulated PTH secretion, which offset the decrease of serum Ca2+; a trade-off phenomenon between negative Ca balance and PTH. This suggests that low Ca2+ dialysate may exaggerate the progression of secondary hyperparathyroidism.

Usefulness of radio-guided surgery using Technetium-99m. Methoxyisobutylisonitrile for primary and secondary hyperparathyroidism

The efficacy of technetium-99m methoxyisobutylisonitrile (99mTc-MIBI)-guided surgery for detecting abnormal parathyroid glands in patients with secondary hyperparathyroidism (2-HPT) was evaluated and compared with the results from the same examination in patients with primary hyperparathyroidism (1-HPT). The results were also compared with those found by ultrasonography (US) and preoperative 99mTc-MIBI scintigraphy was also made. At operation 99mTc-MIBI accumulated in 64 nodules of 15 cases of 2-HPT, and all of 60 parathyroid swellings were detected (true-positives 60, sensitivity 100%, accuracy 94%). In the cases of 1-HPT, 99mTc-MIBI revealed 11 hot nodules in 10 cases, and the evaluation was true-positive 10, sensitivity 100%, and accuracy 91%. US and preoperative 99mTc-MIBI scintigraphy in patients with 2-HPT had a sensitivity of 75% and 67% and an accuracy of 70% and 66%, respectively. The usefulness of 99mTc-MIBI-guided surgery for detecting abnormal parathyroid tissue in 2-HPT patients was similar to that in 1-HPT patients but was superior to US and preoperative 99mTc-MIBI scintigraphy. Intraoperative 9mTc-MIBI for patients with 2-HPT is effective and makes the surgery easier, especially when the parathyroid glands are ectopic or when a few glands are markedly enlarged but the other glands are atrophied.

Hemodialysis Patients Born With a Low Birth Weight Should Have a Different Time Course of Kidney Diseases Than Those Born With a Normal Birth Weight

Low birth weight (LBW) is thought to be one of the risk factors for the progression of kidney diseases. This study hypothesized that the onset age of kidney disease, the rate of progression of kidney disease, or the age at the time of hemodialysis (HD) induction among HD patients that were born with LBW is different from those without a history of LBW. A questionnaire survey in nine dialysis units in Japan was performed and 427 answer sheets were collected. There were statistically significant differences in the present age, the age of kidney disease onset, and the age of HD induction between LBW group and normal birth weight group (NBW). An analysis limited to participants whose underlying disease was diabetic nephropathy revealed that the duration from the onset of nephropathy to HD induction was much shorter in HD patients with a history of LBW than those with a NBW history. In addition, the Pearsons correlation coefficient between the birth weight and the period from onset of diabetic nephropathy to HD induction was 0.283. Although these results might partly support the primary hypothesis, the necessity to perform other clinical studies is also emphasized.

Monitoring of body water composition by the simultaneous use of bioelectrical impedance analysis and Crit-Line® during hemodialysis

BackgroundBioelectrical impedance analysis (BIA) is a non-invasive method to estimate total body water (TBW) and extracellular water (ECW) volume. Crit-Line® (CL), on the other hand, assesses intravascular water (IVW) volume. We evaluate continuous changes in body water composition during hemodialysis (HD) with concurrent use of BIA and CL.MethodsBIA at the start and the end of the HD session was measured using a BIA device. To investigate the shifting pattern of body water composition, patients were subjected to simultaneous monitoring of BIA with CL.ResultsBoth TBW resistance (Rt) and ECW resistance (Re) increased in response to changes in the ultrafiltration (UF) ratio. There was a positive correlation between ΔRe/Rt and the UF ratio, and the ratio of Re/Rt at the end of HD was significantly higher than that at the start of HD. Simultaneous monitoring of BIA with CL showed a parallel shift of the change in the Re (ΔRe) and the change in hematocrit (ΔHt). In one patient with increasing inflammatory response, change in ΔHt was dissociated from change in ΔRe. One hyponatremic patient showed a different pattern of changing ΔRe between the first half and the latter half of the HD session.ConclusionOur study suggests that the concurrent use of BIA and CL may be a useful technique to simulate water shift patterns across the different compartments in HD.