Scottish Trace Element & Micronutrient Reference Laboratory

Scotland's specialised laboratory for trace elements and vitamins in health and disease

Magnesium (Mg)

24 hour urine magnesium is useful in the investigation of unexplained hypomagnesaemia. A low urine magnesium concentration is appropriate for hypomagnesaemia and may suggest inadequate intake or losses from the gastrointestinal system. Urine magnesium results in or above the reference interval may indicate inappropriate urinary loss of magnesium in the face of hypomagnesaemia.

Measurement of random urine magnesium is indicated only for paediatrics with results reported as a creatinine ratio. 


Sample Requirements and Reference Ranges for Magnesium

Sample Type

  Urine (Adults:24 hour collection; Paediatric: Random urine sample)


  Urine: 24 hour urine container or plain universal container for random samples.


  Please mix 24 hour urine well before taking an aliquot.

Minimum volume

  1 mL

Reference ranges

Random Urine99

< 4 weeks                     no reference interval
4wks - 12 months          0.4 - 2.2   mmol/mmol creat.
1 - 2 years                    0.4 - 1.7
2 - 3 years                    0.3 - 1.6
3 - 5 years                    0.3 - 1.3
5 - 7 years                    0.3 - 1.0
7 - 10 years                  0.3 - 0.9

> 10yrs                        0.2 – 0.7  


24 hour urine100

0 – 10  years                no reference interval
>10 years                    2.4 – 6.5 mmol/24hr

Turnaround time

  See this page for STEMDRL TAT targets


  Inductively coupled plasma mass spectrometry


Traceable to reference material produced in accordance with EN ISO 17511:2003 “In vitro diagnostic medical devices. Measurement of quantities in biological samples. Metrological traceability of values assigned to calibrators and control materials” and reference materials with values determined by reference laboratories.

Intermediate Precision (CV)

  See this page for latest data

Measurement Uncertainty, U

  See this page for latest data

Analytical Goals (CV)

  See this page for latest data

EQA Scheme

  UK NEQAS, Birmingham (once per month).

Included in UKAS scope?



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