Biochemical Calculations

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	Biochemical Calculations
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Renal Calculations	Creatinine Clearance Calculated Creatinine Clearance (Cockcroft & Gault) On-line Calculator (umol/L) Calculated Creatinine Clearance (Lean Body Mass est'd from height) On-line Calculator (umol/L) Fractional Excretion of Sodium (FENA) Creatinine Clearance - correction for body surface area
General Calculations	LDL Cholesterol Transferrin Saturation Indirect Bilirubin Calcium corrected for albumin	Half-Life Calculator Unit Conversions Web Chemistry calculator
Renal Calculations	Creatinine Clearance (calculated from creatinine measured in 24 hours urine and plasma collections) Creatinine Clearance (mL/s) = {U Creat x Vol x 1000} / {Pl Creat x Time x 60 x 60} Urine and plasma creatinine concentrations in mmol/L; Volume in mL *For serum creatinine measurements in umol/L:* Creatinine Clearance (mL/s) = {U Creat x Vol x 1000 x 1000} / {Pl Creat x Time x 60 x 60} Urine creatinine concentration in mmol/L and serum creatinine concentrations in umol/L; Volume in mL Reference Interval: 1.5 - 2.5 mL/s Notes: Creatinine excretions >20 mmol/d or <5 mmol/d may indicate prolonged or incomplete collections. Plasma creatinine should be collected within the period of urine collection. Plasma creatinine from outside this period may be acceptable if renal function is stable. Return to top Calculated Creatinine Clearance (Cockcroft and Gault) (estimated from plasma creatinine, age, wt and sex) Creatinine Clearance (mL/s) = {(140 - Age)} x Wt x F}/ {P CREAT x 48816} F= 1 (males); F=0.85 (females) Age in years Plasma creatinine concentration in mmol/L Weight in kg *For serum creatinine measurements in umol/L:* Creatinine Clearance (mL/s) = {(140 - Age)} x Wt x F}/ {P CREAT x 48.816} F= 1 (males); F=0.85 (females) Age in years Plasma creatinine concentration in umol/L Weight in kg Reference Interval: 1.5 - 2.5 mL/s Notes: Extremes of body composition may affect accuracy of estimation. On-line Calculator for Cockcroft and Gault Equation Return to top Calculated Creatinine Clearance (Cockcroft and Gault) with Lean body Mass estimated from patient height (estimated from plasma creatinine, age, height and sex) Creatinine Clearance (mL/s) = {(140 - Age)} x Wt x F}/ {P CREAT x 48816} F= 1 (males); F=0.85 (females) Age in years Plasma creatinine concentration in mmol/L Weight in kg *For serum creatinine measurements in umol/L:* Creatinine Clearance (mL/s) = {(140 - Age)} x Wt x F}/ {P CREAT x 48.816} F= 1 (males); F=0.85 (females) Age in years Plasma creatinine concentration in umol/L Weight in kg Reference Interval: 1.5 - 2.5 mL/s Estimated Lean Body Mass from patient's height: Males (kg) = 50 kg plus 0.9 kg for every cm of height > 150 cm Females (kg) = 45 kg plus 0.9 kg for every cm of height > 150 cm Notes: Extremes of body composition may affect accuracy of estimation. On-line Calculator for Cockcroft and Gault Equation Return to top Fractional Excretion Of Sodium (FENA) FENA(%) = {U Na / Pl Na x 100} / {U Cr / Pl Cr} All concentrations in mmol/L Interpretation: In pre-renal renal failure FENA is generally <1%. Return to top Creatinine Clearance Per M² Body Surface Area (BSA) BSA(m²) = 0.0235 x Ht(cm)^0.42246 x wt(kg)^0.51456 CrCl(mL/s/1.73m²) = U CRCL(mL/s) x 1.73/BSA(m²) Return to top
General Calculations	LDL Cholesterol (LDLC) LDLC (mmol/L) = Total Cholesterol - HDLCholesterol - (Triglycerides / 2.2) All values in mmol/L Notes: If the triglyceride concentration is > 4.5 the calculation is not valid and cannot be used. Return to top Transferrin Saturation (%SAT) %SAT = 3.982 x Iron (umol/L) / Transferrin (g/L) Return to top Indirect Bilirubin Indirect Bilirubin (umol/L) = Total Bilirubin (umol/L) - Direct Bilirubin (umol/L) Indirect bilirubin is a measure of unconjugated bilirubin Direct bilirubin is a measure of conjugated bilirubin Return to top Calcium Corrected for Albumin Used to correct plasma total calcium measurements for effects of changes in albumin concentration. Corrected calcium can then be compared with usual reference intervals. Calcium (corrected, mmol/L) = Calcium (measured, mmol/L) + {(40 - albumin (g/L)) x 0.02} Notes: The correction can be applied to elevated as well as decreased serum albumin The correction only applies to total calcium The correction is a guide only. Return to top
	Last Updated 16/12/2004 Disclaimer Return to top Maintenance