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Abstract: SA-PO264

Circadian Rhythm of Plasma Magnesium in Patients with CKD Stage 3-4 and Healthy Controls

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical


  • Jacobsen, Alexanndra, Department of Nephrology, Herlev Hospital, Copenhagen, Denmark
  • Bressendorff, Iain Oshoj, Department of Nephrology, Herlev Hospital, Copenhagen, Denmark
  • Nordholm, Anders, Herlev Hospital, Herlev, Denmark
  • Egstrand, Søren, Nephrological Department P, Rigshospitalet, Copenhagen, Denmark
  • Jørgensen, Niklas Rye, Rigshospitalet, Glostrup, Denmark
  • Lewin, Ewa, University of Copenhagen, Copenhagen, Denmark
  • Olgaard, Klaus, Rigshospitalet, Glostrup, Denmark
  • Hansen, Ditte, Herlev Hospital, Herlev, Denmark

Chronic kidney disease (CKD) is associated with vascular calcification leading to cardiovascular morbidity and mortality. Decreasing levels of plasma magnesium (Mg) are associated with increased risk of cardiovascular disease in patients with CKD, which might be amendable to Mg supplementation. Several biochemical parameters follow a circadian rhythm, which may affect the way these parameters should be measured and may be of importance for their physiological effects and interaction. The aim of this study was to identify the circadian rhythm of plasma Mg in CKD.


This was an investigator-initiated observational clinical trial. Subjects included were patients with CKD 3-4 without diabetes (n=10 (9 males)) and healthy controls (n=10 (5 males)). Venous blood and urine samples were collected non-fasting at 8 a.m. and every third hour during a 24-hour admission with the final collection in fasting state at 8 a.m. the following day.


The baseline mean (± SD) eGFR was 27 ± 8 mL/min/1.73m2 in patients with CKD and 105 ± 10 mL/min/1.73m2 in healthy controls. The overall mean (± SD) plasma Mg in patients with CKD was not significantly higher than in healthy controls (0.88 ± 0.04 mmol/L versus 0.84 ± 0.07 mmol/L (p = 0.220)). Cosinor analysis revealed no significant diurnal variation in plasma Mg in either subjects with CKD (p = 0.23) or healthy controls (p = 0.29). There was no significant difference between plasma Mg levels (mean ± SD) in fasting and non-fasting state in patients with CKD (fasting 0.90 ± 0.13 mmol/L and non-fasting 0.90 ± 0.06 mmol/L (p = 0.907)) or healthy controls (fasting 0.84 ± 0.07 mmol/L and non-fasting 0.83 ± 0.09 mmol/L (p = 0.598)).


Plasma Mg exhibits no diurnal variation and is not affected by fasting in patients with CKD 3-4. Evaluation of plasma magnesium levels in patients with CKD 3-4 requires no special precaution concerning the time of the day for sampling or whether the patient is in fasting state.