Kaye M, Vasilevsky M, Ketis M
Division of Nephrology, Montreal General Hospital, Quebec, Canada.
Clin Nephrol. 1998 Dec;50(6):361-6.
Elevating serum ionized calcium levels is known to stabilize blood pressure during and after a hemodialysis session. The data on lowering calcium levels is limited.
This study examined the responses to an acute drop in ionized calcium during a four hour hemodialysis session in two subjects who differed in the presence (patient 1) or absence (patient 2) of anti-hypertensive medication and average weight loss of 4 kg (patient 1) or 2 kgs (patient 2) with each dialysis. Parathyroid hormone (PTH) levels were normal (patient 1) or very high (patient 2). A calcium free dialysate was used and the calcium infusion rate distal to the dialyzer was varied to produce either no change in ionized calcium for 10 dialyses, or a fall of at least 0.2 mmol/l for 10 dialyses. The sequence was randomized and was blinded to the observers and patients.
The fall in ionized calcium was similar in each individual, 0.37 +/- 0.11 and 0.34 +/- 0.05 mmol/l. PTH rose from 8.6 +/- 1.6 to 24.2 +/- 6.6 pmol/l for patient 1 and 144.6 +/- 59.9 to 234.8 +/- 32.3 pmol/l for patient 2: patient 1 showed a fall in blood pressure after dialysis associated with the fall in calcium. This was most pronounced in the upright position whereas there was no change for Patient 2. For Patient 1 standing mean blood pressure post-dialysis was 104 +/- 6 mmHg when the calcium was stable and 94 +/- 10 mmHg with hypocalcemia p <0.01. Mean blood pressure during dialysis was also lower with hypocalcemia 100 +/- 7 versus 92 +/- 9 p <0.05. There were no significant changes in blood pressure for patient 2. Neither of the patients had any symptoms attributable to hypotension or hypocalcemia.
It was concluded that modest falls in ionized calcium were associated with a drop in standing blood pressure only when combined with other factors predisposing to vascular instability. Even so these decreases were small enough to be asymptomatic.
已知提高血清离子钙水平可在血液透析期间及之后稳定血压。关于降低钙水平的数据有限。
本研究检测了两名受试者在四小时血液透析期间对离子钙急性下降的反应，这两名受试者在是否服用抗高血压药物以及每次透析平均体重减轻4千克（患者1）或2千克（患者2）方面存在差异。甲状旁腺激素（PTH）水平正常（患者1）或非常高（患者2）。使用无钙透析液，并改变透析器远端的钙输注速率，在10次透析中使离子钙无变化，或在10次透析中使其至少下降0.2毫摩尔/升。顺序是随机的，对观察者和患者均设盲。
每位受试者的离子钙下降情况相似，分别为0.37±0.11和0.34±0.05毫摩尔/升。患者1的PTH从8.6±1.6皮摩尔/升升至24.2±6.6皮摩尔/升，患者2的PTH从144.6±59.9皮摩尔/升升至234.8±32.3皮摩尔/升：患者1在透析后血压下降与钙下降相关。这在直立位时最为明显，而患者2没有变化。对于患者1，透析后站立时的平均血压在钙稳定时为104±6毫米汞柱，低钙血症时为94±10毫米汞柱，p<0.01。低钙血症时透析期间的平均血压也较低，分别为100±7和92±9，p<0.05。患者2的血压没有显著变化。两名患者均没有任何归因于低血压或低钙血症的症状。
得出的结论是，只有在与其他易导致血管不稳定的因素相结合时，离子钙的适度下降才与站立血压下降相关。即便如此，这些下降幅度小到没有症状。
