Internal Medicine
47 calculators
Core clinical calculators for acid-base analysis, fluid and electrolyte management, renal function, and metabolic assessment.
Related Categories
CKD-EPI 2021 eGFR Equation
Estimates glomerular filtration rate (eGFR) using the 2021 CKD-EPI creatinine equation.
NephrologyIdeal 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 MedicineCockcroft-Gault Equation
Estimates creatinine clearance (CrCl) for medication dosing using the Cockcroft-Gault equation.
NephrologyChild-Pugh Score
Estimates severity and prognosis of chronic liver disease and cirrhosis.
Internal MedicineBUN/Creatinine Ratio
Calculates the Blood Urea Nitrogen to Creatinine ratio to help differentiate causes of kidney dysfunction.
NephrologyMDRD GFR Equation
Estimates glomerular filtration rate using the 4-variable MDRD equation.
NephrologyCorrected Calcium
Calculates corrected total serum calcium adjusted for hypoalbuminemia. In hypoalbuminemia, measured total calcium is falsely low because less calcium is protein-bound; this correction estimates the physiologically active total calcium.
LaboratoryAnion 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 MedicineFractional Excretion of Sodium (FENa)
Calculates the fractional excretion of sodium to distinguish prerenal azotemia from acute tubular necrosis.
NephrologyFractional Excretion of Urea (FEUrea)
Calculates the fractional excretion of urea for renal evaluation, particularly useful when diuretics are present.
NephrologyTranstubular Potassium Gradient (TTKG)
Calculates the transtubular potassium gradient to assess renal potassium handling.
NephrologyCalcium-Phosphate Product
Calculates the calcium-phosphate product used in renal risk assessment for vascular calcification.
NephrologyFractional Excretion of Uric Acid (FEUA)
Calculates the fractional excretion of uric acid (FEUA) to help distinguish prerenal azotemia from intrinsic renal injury in acute kidney injury, and to assess uric acid handling (e.g., SIADH, tumor lysis, Fanconi syndrome).
NephrologyFractional Excretion of Phosphate (FEP)
Calculates the fractional excretion of phosphate (FEP) to localize the cause of hypophosphatemia: a high FEP indicates renal phosphate wasting, whereas a low FEP suggests redistribution or extrarenal loss.
NephrologyFractional Excretion of Calcium (FECa / Calcium–Creatinine Clearance Ratio)
Calculates the fractional excretion of calcium (calcium–creatinine clearance ratio, CCCR) to help distinguish familial hypocalciuric hypercalcemia (FHH) from primary hyperparathyroidism in patients with hypercalcemia and non-suppressed PTH.
NephrologyRenal Failure Index (RFI)
Calculates the renal failure index (RFI), a classic urinary index that uses urine sodium relative to the urine:plasma creatinine ratio to help distinguish prerenal azotemia from acute tubular necrosis (ATN).
NephrologyUrine Osmolal Gap (UOG)
Calculates the urine osmolal gap — the difference between measured and estimated urine osmolality — to detect unmeasured osmoles in the urine (e.g., ethylene glycol, mannitol, or other toxins).
NephrologyFree Water Clearance (CH₂O)
Calculates renal free water clearance (CH₂O) from urine flow, urine osmolality, and plasma osmolality to characterize renal water handling in polyuria, hyponatremia, and hypernatremia.
NephrologyElectrolyte-Free Water Clearance (EFWC)
Calculates urinary electrolyte-free water clearance (EFWC) from urine flow and urinary/plasma sodium and potassium. It is used to distinguish renal from extrarenal water losses and to guide fluid therapy in dysnatremia.
NephrologyUrine Protein-to-Creatinine Ratio (UPCR)
Calculates the urine protein-to-creatinine ratio (UPCR) from a spot urine sample to estimate 24-hour proteinuria for CKD detection, monitoring, and nephrotic range proteinuria screening.
NephrologyTotal Cholesterol / HDL Ratio (TC/HDL)
Calculates the total cholesterol to HDL ratio (TC/HDL), a lipid-based cardiovascular risk indicator that compares total cholesterol with the protective HDL fraction.
LaboratoryAtherogenic Index of Plasma (AIP)
Calculates the atherogenic index of plasma (AIP), a logarithmically transformed ratio of triglycerides to HDL cholesterol that reflects the balance of atherogenic and protective lipoproteins.
LaboratoryApoB / ApoA1 Ratio (ApoB:ApoA1)
Calculates the apolipoprotein B to apolipoprotein A1 ratio (ApoB:ApoA1), an index of the balance between atherogenic (ApoB) and anti-atherogenic (ApoA1) lipoproteins used in cardiovascular risk assessment.
LaboratoryRespiratory 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 MedicineCalculated LDL (Friedewald Equation)
Estimates low-density lipoprotein cholesterol (LDL-C) from a standard fasting lipid panel using the Friedewald equation: LDL = total cholesterol − HDL − (triglycerides / 5). Used for cardiovascular risk assessment and lipid-lowering treatment targets. Not valid when triglycerides are ≥ 400 mg/dL.
LaboratoryNon-HDL Cholesterol
Calculates non-HDL cholesterol (total cholesterol minus HDL cholesterol). Non-HDL captures all atherogenic apolipoprotein B-containing lipoproteins, including LDL, VLDL, IDL, and remnants, and is a secondary lipid treatment target per ATP III guidelines.
LaboratoryAlbumin to Globulin Ratio (A/G)
Calculates the albumin to globulin ratio from serum albumin and total protein (A/G ratio = albumin / (total protein − albumin)). The ratio is used as a screening aid in the evaluation of liver disease, nephrotic syndrome, and monoclonal gammopathies, alongside the absolute albumin and globulin values.
LaboratoryWinter'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 MedicineUrine Anion Gap (UAG)
Calculates the urine anion gap: UAG = (urine sodium + urine potassium) − urine chloride. It is used to distinguish renal from extrarenal (gastrointestinal) causes of a normal anion gap (hyperchloremic) metabolic acidosis with hypokalemia and normal renal function.
NephrologyCorrected Magnesium (Albumin-Adjusted)
Adjusts measured serum magnesium for hypoalbuminemia. When serum albumin is low, measured total magnesium is falsely reduced because less magnesium is bound to proteins. This correction estimates the physiologically relevant magnesium level.
LaboratorySerum-Ascites Albumin Gradient (SAAG)
Calculates the gradient between serum albumin and ascitic fluid albumin to classify ascites as portal hypertensive (SAAG ≥1.1 g/dL) or non-portal hypertensive (SAAG <1.1 g/dL). First-line diagnostic tool for ascites workup.
GastroenterologyALBI Score (Albumin-Bilirubin)
Objective prognostic assessment of liver function using serum albumin and bilirubin. Primarily validated in hepatocellular carcinoma (HCC) for stratifying prognosis and guiding treatment decisions.
Gastroenterology