Kidney Week

Abstract: FR-PO298

24-Hour Urine Magnesium Excretion in a Multi-Ethnic Asian Population of CKD and Healthy Participants

Session Information

• Fluid and Electrolytes: Clinical
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid and Electrolytes

• 902 Fluid and Electrolytes: Clinical

Authors

• Khan, Umer Farooq, National University Hospital Singapore, Singapore, Singapore

Umer Farooq Khan,

• Lau, Titus W., National University Health System, Singapore, Singapore

Titus W. Lau,

• Teo, Boon Wee, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

Boon Wee Teo,

Background

Magnesium (Mg) is implicated in bone metabolism, vascular tone, cardiovascular risk, and immunity. Its homeostasis is affected by diet, gut absorption, and kidney filtration, reabsorption, and excretion. Previous studies demonstrated an increase in serum Mg and urine fractional excretion of Mg (FEMg) in chronic kidney disease (CKD). The 24-hour urinary Mg (24UMg; mmol) excretion in a multi-ethnic Asian population of CKD and healthy participants without kidney disease is unknown. We aim to characterize serum Mg, 24UMg, and FEMg in a multi-ethnic Asian population.

Methods

Out of 335 (51% male) consenting participants, 232 (69%) were patients with CKD, and 103 (31%) were healthy individuals without kidney disease, diabetes, or hypertension. Following a 24-hr urine collection, participants underwent glomerular filtration rate (GFR; mL/min/1.73m²) measurement using Tc^99mDTPA, and provided a spot urine and blood. No patients were on Mg supplementation. Data were analyzed on SPSS V23 using standard statistical tests, where appropriate.

Results

Of the 232 patients with CKD, 72 (31.0%) had GFR >60, 99 (42.7%) had GFR 30-60, and 61 (26.3%) had GFR <30; 51.3% were diabetic, and 82.8% were hypertensive. Mean 24UMg values were lower in patients with CKD (2.50±1.25) than healthy participants (2.93±1.45) [p=0.006]. Patients with GFR <30 had lower mean 24UMg values (2.00±1.10) compared to groups 30-60, and >60 (2.64±1.20, 2.75±1.34, respectively) [p=0.001]. Group with GFR <30 had a higher mean serum Mg (p=0.005) and an increased FEMg (p<0.001).
24UMg is associated with GFR (24UMg=2.032+0.009×GFR, p=0.002], which persists after excluding patients on diuretics. 24UMg and GFR is positively correlated in CKD patients with hypertension but not in non-hypertensives and diabetic patients.

Conclusion

Healthy participants have higher 24UMG excretion than CKD patients. With reduced GFR, serum Mg is higher, and 24UMg is lower, and is associated with an increased FEMg in Asian CKD patients.