Appendix 12. Dose adjustments in renal insufficiency

Update: January 2022

12.1 Normal values for creatinine clearance (CrCl)

Women: 88 to 128 ml/minute
Men: 97 to 137 ml/minute

12.2 Estimation of CrCl (Cockcroft-Gault method)

12.2.1 If serum creatinine is in µmol/litre

    Weight (kg) x (140 – age) x (constant)
–––––––––––––––––––––––––––––––––––––
          Serum creatinine (µmol/litre)

The constant = 1.04 for women and 1.23 for men

12.2.2 If serum creatinine is in mg/dl

       Weight (kg) x (140 – age)
–––––––––––––––––––––––––––––
   72 x serum creatinine (mg/dl)

For women, the result must be multiplied by 0.85.

Example (calculation with serum creatinine in µmol/litre) aCitation a.If possible use a calculator to avoid errors, e.g.:
https://www.mdcalc.com/creatinine-clearance-cockcroft-gault-equation :
A woman on cycloserine (Cs), 50 kg, 46 years, serum creatinine = 212 µmol/litre

• Step 1 - Calculate the CrCl:
  50 x (140 – 46) x 1.04 = 4,888
  4,888 ÷ 212 = 23.1
  For this patient, the CrCl is 23.1 ml/minute
• Step 2 - CrCl is < 30 ml/minute, administer 250 mg of Cs once daily or 500 mg 3 times a week.
• Step 3 - Adjust each drug as required according to the table below.

12.2.3 Overweight and obese patients

For overweight (BMI > 25) or obese (BMI > 30) patients, use the ideal body weight (IBW) rather than the actual body weight to avoid overestimation of the CrCl. 

The IBW is calculated using the patient’s height bCitation b.If possible use a calculator to avoid errors, e.g.:
https://www.mdcalc.com/ideal-body-weight-adjusted-body-weight :
IBW women (kg) = 45.4 + 0.89 (height in cm – 152.4)
IBW men (kg) = 49.9 + 0.89 (height in cm – 152.4)

Example:
A woman, weight 70 kg, height 160 cm (BMI = 27.3, i.e. overweight)
45.4 + 0.89 (160 – 152.4) = 45.4 + 0.89 (7.6) = 45.4 + 6.76 = 52.2
For this patient, the IBW is 52 kg.

12.3 Dosing of TB drugs in renal insufficiency