Internal Medicine
21 calculators
General internal medicine tools for acid-base analysis, fluid management, and metabolic assessment.
Related Specialties
Ideal Body Weight
Calculates Ideal Body Weight using the Devine formula.
Internal MedicineAdjusted Body Weight
Calculates Adjusted Body Weight using the Devine Ideal Body Weight formula.
Internal MedicineLean Body Weight
Calculates Lean Body Weight using the Boer formula.
Internal MedicineChild-Pugh Score
Estimates severity and prognosis of chronic liver disease and cirrhosis.
Internal MedicineAnion Gap
Calculates the serum anion gap using sodium, chloride, and bicarbonate. The anion gap helps differentiate high anion gap metabolic acidosis (HAGMA) from normal anion gap metabolic acidosis (NAGMA).
Internal MedicineCorrected Anion Gap
Calculates the albumin-corrected anion gap. In hypoalbuminemia, the measured anion gap is falsely low, potentially masking a high anion gap metabolic acidosis. This correction adjusts for the albumin contribution.
Internal MedicineSerum Osmolality
Calculates the estimated serum osmolality using sodium, glucose, and blood urea nitrogen (BUN). Useful in evaluating electrolyte disorders, dehydration, toxic alcohol ingestion, and calculating the osmolar gap.
Internal MedicineOsmolar Gap
Calculates the osmolar gap as the difference between measured and calculated serum osmolality. An elevated osmolar gap may suggest toxic alcohol ingestion (methanol, ethylene glycol) or other osmotically active substances.
Internal MedicineBasal Metabolic Rate
Estimates basal metabolic rate using the Mifflin-St Jeor equation.
Internal MedicineHarris-Benedict
Estimates basal metabolic rate using the Harris-Benedict equation.
Internal MedicineCalorie Requirement
Estimates daily calorie requirement from basal metabolic rate and activity level.
Internal MedicineFluid Requirement
Estimates maintenance fluid requirement based on body weight.
Internal MedicineMaintenance Fluids
Estimates maintenance fluid rate using a weight-based method.
Internal MedicineFree Water Deficit
Estimates free water deficit in hypernatremia. Helps quantify the amount of free water needed to restore normal sodium levels.
Internal MedicineSodium Deficit
Estimates sodium deficit for hyponatremia correction planning. Helps determine the total amount of sodium needed to raise serum sodium to a target level.
Internal MedicineCorrected Sodium
Corrects serum sodium for hyperglycemia using the conventional correction factor. Hyperglycemia draws water into the extracellular space, diluting sodium; this correction estimates what sodium would be at a normal glucose level.
Internal MedicineRespiratory Compensation Calculator (Expected Bicarbonate)
Estimates the expected serum bicarbonate during acute or chronic respiratory acidosis and alkalosis using the Winters/Merck compensation rules, helping to identify whether a metabolic disturbance is appropriately compensated or a mixed disorder is present.
Internal MedicineMetabolic Alkalosis Compensation (Expected PaCO₂)
Calculates the expected arterial PaCO₂ in metabolic alkalosis (PaCO₂ ≈ 40 + 0.6 × (HCO₃ − 24)) to assess whether respiratory compensation is appropriate or whether a concurrent respiratory disorder is present.
Internal MedicineWinter's Formula (Expected PaCO2 in Metabolic Acidosis)
Calculates the expected compensatory respiratory response to a primary metabolic acidosis: expected PaCO2 = 1.5 × HCO3 + 8 ± 2 mmHg. It is used to determine whether the respiratory response is appropriate, inadequate (respiratory acidosis), or excessive (respiratory alkalosis).
Internal MedicineAnion Gap Delta Ratio (ΔAG/ΔHCO3)
Calculates the anion gap delta ratio to evaluate the acid-base response in a high anion gap metabolic acidosis: ΔAG/ΔHCO3 = (measured anion gap − 12) / (24 − measured HCO3). It helps identify mixed acid-base disorders such as a concurrent non-anion gap acidosis or metabolic alkalosis.
Internal MedicineCharlson Comorbidity Index (CCI)
The Charlson Comorbidity Index (Charlson 1987) predicts one-year and ten-year mortality from a weighted count of 19 comorbidities (weights 1, 2, 3, and 6) plus an age adjustment (per decade over 40, 1994). Higher scores indicate greater comorbidity burden and lower estimated ten-year survival, with wide application as a case-mix adjustment in outcomes research and clinical prognostication.
General Medicine