Blood Sciences Test

Calcium / Creatinine Ratio

Taken from

Endocrinology Handbook

Endocrine Unit

Imperial College Healthcare NHS Trust

Charing Cross, Hammersmith and St. Mary’s Hospitals

Updated: March 2010

Confirmation of Hyperparathyroidism



Calcium Clearance

[Urine Calcium (mmol/l) x urine volume (ml)] / [ Serum Calcium (mmol/l) x 1440]


Creatinine Clearance  (This may be calculated already)

[Urine Creatinine (mmol/l) x urine volume (ml)] / [ Serum Creatinine (mmol/l) x 1440]

Serum creatinine is normally expressed in umol/l and needs to be converted to mmol/l by dividing by 1000.


However, this ratio can be reduced to:

Urine Calcium (mmol/l) x [Serum Creatinine (umol/l) / 1000]

Serum Calcium (mmol) x Urine Creatinine (mmol/l)

For example


Urine calcium 1.0 mmol/l                     Ratio = 1.0 x [130/1000] = 0.0079

Urine creatinine 6.2 mmol/l                                        2.65 x 6.2

Serum creatinine 130 umol/l

Serum  calcium 2.65 mmol/l


Primary Hyperparathyroidism

Urine calcium 2.2mmol/l                               Ratio = 2.2 x [74/1000] = 0.035

Urine creatinine 1.4 mmol/l                                        3.3 x 1.4

Serum creatinine 74 umol/l

Serum calcium 3.3 mmol/l


Please note this test is not UKAS accredited

Specimen Labelling Procedure