What is the relationship between Hypocalcemia and dialysis?

From the Guidelines

Hypocalcemia is a significant concern in patients undergoing dialysis, as it can contribute to the pathogenesis of secondary hyperparathyroidism (SHPT) and renal osteodystrophy 1.

Key Points

• Dialysate calcium concentration is crucial in managing hypocalcemia in patients with chronic kidney disease (CKD) stage G5D, with a suggested concentration between 1.25 and 1.50 mmol/L (2.5 and 3.0 mEq/L) 1.
• Hypocalcemia may have increased after the introduction of calcimimetics (cinacalcet) in patients receiving dialysis, but the clinical implications of this increased incidence are uncertain 1.
• Individualized approach should be used to treat hypocalcemia, rather than recommending correction of hypocalcemia in all patients, as the benefits of calcimimetic treatment are unproven and may pose potential harm 1.
• Significant or symptomatic hypocalcemia can still benefit from correction to prevent adverse consequences, such as increased mortality, incidence of fractures, and bone disease 1.
• Net calcium absorption is reduced in chronic renal failure, and dietary calcium intake is often low in patients with CKD, making it essential to monitor and manage calcium levels carefully 1.
• Dialysate calcium concentration may need to be adjusted to maintain a neutral calcium balance and prevent secondary hyperparathyroidism, with some studies suggesting a concentration of 1.5 mmol/L or higher 1.

From the Research

Relationship between Hypocalcemia and Dialysis

• Hypocalcemia is a common abnormality in patients receiving dialysis therapy, and it can be asymptomatic or symptomatic 2.
• The relationship between hypocalcemia and dialysis is complex, and hypocalcemia can drive hyperparathyroidism, leading to gland hypertrophy and autonomous function 2.
• Hidden hypocalcemia, defined as low ionized calcium levels despite normal or high corrected calcium levels, is a significant risk factor for cardiovascular events and all-cause mortality among patients undergoing incident hemodialysis 3.
• True hypocalcemia, defined as ionized calcium <1.15 mmol/L, is a significant risk factor for cardiovascular events and all-cause mortality, whereas hypocalcemia defined as corrected calcium <8.4 mg/dL is not 3.

Causes and Predictors of Hypocalcemia in Dialysis Patients

• Spontaneous parathyroid gland infarction can cause hypocalcemia in end-stage renal disease patients 4.
• Preoperative serum alkaline phosphatase (ALP) is an independent predictor of postoperative severe hypocalcemia in dialysis patients with secondary hyperparathyroidism after near-total parathyroidectomy 5.
• Patients with preoperative serum ALP levels >277 U/L are susceptible to postoperative severe hypocalcemia 5.

Management of Hypocalcemia in Dialysis Patients

• Calcium control by dialysis is mainly dependent on its mass balance, which is influenced by the calcium concentration difference between blood and dialysis solutions and by the duration of the treatment 6.
• The ideal calcium concentration in dialysis fluids is still a matter of debate, but a lower calcium concentration in standard hemodialysis treatment (1.25-1.50 mmol/l) is suggested 6.
• Phosphate dialysis balance is also a critical problem, and increasing phosphate removal can be obtained with high-efficiency techniques, such as hemodiafiltration, or by increasing dialysis duration 6.