Medical Calculator with Equations and Interpretations

Click on name of equation to see formula and edit input boxes to automatically calculate result.

Convert between Pounds and Kilograms and between Inches and Centimeters

kg * 2.2 = lbs
cm = 2.54 * inches

Alveolar-Arterial O2 Gradient

= FiO2 * (pAtm - pH2O) - paO2 - pCO2 / RQ = _____
pAtm = 760 mmHg * exp(-altitude / 7000)
pH2O = 47 mmHg @ 37 degrees Celcius
FiO2 (%):
altitude (Sacramento is 7 meters):
paO2 (mmHg):
pCO2 (mmHg):
RQ (respiratory quotient):

Anion Gap

= Na - (Cl + HCO3) = _____
Na:
Cl:
HCO3:
Interpretation: Normal range is 8 - 16. If high, remember MUDPILES (Methanol, Uremia, Dka, Paraldehyde, INH/Iron, Lactic acid, Ethanol, Salicylates)

APGAR

= _____
color: pink extremities blue body blue
tone: active some flexion limp
pulse: HR >= 100 < 100 no pulse
respiration: crying irregular respirations or slow absent
response to suction: sneeze or cough grimace no reaction
Interpretation: most babies 7-10, points off for color and tone

Body Mass Index, (BMI)

= weight / square of height = _____
weight (kg):
height (m):
Interpretation:
  less than 18.5 => underweight
  18.5 - 25 => normal weight
  25 - 30 => overweight
  greater than 30 => obese

Basal Metabolic Rate (Harris-Benedict)

(male) = 13.7516 * kg + 5.0033 * cm - 6.755 * yrs + 66.473
(female) = 9.5634 * kg + 1.8496 * cm - 4.6756 * yrs + 655.095
= ________ kcal/day
   weight (kg): , height (cm): , age (yrs): , gender: Male   Female

Corrected Calcium

= Ca + 0.8 * (4 - Alb) = _____ Ca: Alb:

Child-Pugh Score

= _____
Bilirubin: <2 2-3 >3
Albumin: >3.5 3.5-2.8 <2.8
PT prolongation (INR): <4 seconds (<1.7) 4-6 seconds (1.7-2.3) >6 seconds (>2.3)
Ascites: Absent Mild-Moderate Severe/Refractory
Encephalopathy: Absent Mild (I-II) Severe (III-IV)

Creatinine Clearance (Cockcroft-Gault)

(male) 1.23 * kg * (140 - years) / Cr
(female) 1.03 * kg * (140 - years) / Cr
= _____
gender: Male   Female
weight (kg):
age (years):
Creatinine (mg/dL):

Corrected Na

= Na + (glc - 5) / 3.5 = _____
Na (mmol/L): glc (mg/dL):

Fractional Excretion of Sodium, (FENa)

= (UNa / UCr) * (PCr / PNa) = _____%
Na, plasma (mmol/L):
Cr, plasma (mmol/L):
Na, urine (mmol/L):
Cr, urine (mmol/L):
Interpretation: less than 1% implies Prerenal azotemia

Free Water Deficit

(Male) = 0.5 * kg * ((Na / 140) - 1)
(Female) = 0.4 * kg * ((Na / 140) - 1)
= _____
gender: Male Female
weight (kg):
Na (mmol/L):
Interpretation: max 1/2 deficit replace in 1st 24hrs

Fluid Replacement, Parkland formula

= weight * % BSA burned * 4 = _____(L)
weight (kg):
% Body Surface Area burned (%):
Interpretation: 1/2 first 8hrs, 1/2 next 16hrs

Glomerular Filtration Rate, (GFR)/CKD Staging

(female, black) = 186 * Cr ^ -1.154 * age^-0.203 * 1.210 * 0.742
(??, ??) = 170 * Cr ^ -1.007 * age^-0.180 * 1.178 * 0.755 * BUN ^ 0.169
(??, ??) = 170 * Cr ^ -0.999 * age^-0.176 * 1.180 * 0.762 * BUN ^ 0.17 * alb ^ 0.318
= _____
gender: Male Female
African-American ethnicity:
age (years):
BUN (units):
Cr (mg/dL):
alb (units):

Osmotic Gap

= measured osmolals - 2 * Na + BUN / 2.8 + glc = _____
measured Osmolals (units):
Na (mmol/L):
BUN (units):
glc (mg/dL):

Delta-Delta Gap

delta HCO3 = 24 - HCO3 =
expected AG = albumin x 2.5 =
AG = Na - (Cl + HCO3) =
delta AG = AG - expected AG =
delta-delta = delta HCO3 - delta AG
= _____
Na:
Cl:
HCO3 (units):
alb:
Interpretation:
delHCO3 ~ delAG, ~0 --> pure AG metabolic acidosis
delHCO3 > delAG, >0 --> simultaneous non-AG acidosis
delHCO3 < delAG, <0 --> simultaneous metabolic ALKalosis

Glasgow Coma Scale, adults

= _____
Eye opening (none/pain/speech/spontaneous)
Verbal communication (none/sounds/words/confused/oriented)
Motor (none/abnormal extension/abnormal flexion/withdraw pain/localize pain/spontaneous or obeys commands)
Interpretation: less than 8 is coma.

LDL goals from ATP III

Major CHD Risk Factors: Cigarette smoking, Hypertension, HDL<40, age (man >45, female >55), family history of premature CHD (male age <55, female age <65)
LDL goals based on # risk factors:
  0-1 => less than 160
  2+ => less than 130
  CHD => less than 100
  DM => less than 70
Criteria for choosing a lipid lowering agent:
Drug%LDL reduction%HDL increase%TG reductionSide Effects (monitoring & contraindications)
statin18-555-157-30myopathy, increased LFT
sequestrant15-303-5nil - increaseGI, constipation, decreased drug absorption
Niacin5-2515-3520-50flushing, hyperglc, gout, LFT, UGI
fibric acid5-2010-2020-50dyspepsia, gallstones, myopathy, (LFT, Cr)

Severe I Respiratory Syndrome, (SIRS)

2 or more of HR>90, T<36 or T>38, RR >20 or PaCO2 <32, WBC <4 or >12

Ideal Body Weight, (IBW), (Robinson Formula)

(men) = 52 + 1.9 * (in - 60)
(women) = 49 + 1.7 * (in - 60)
= _____

PORT Scoring

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