A focused collection of 35 calculators, scores, and clinical references.
25(OH)D Level–CV Mortality Index: Explanation and Clinical Context The 25(OH)D Level–CV Mortality Index estimates the 10-year risk of cardiovascular mortality based on circulating 25-hydroxyvitamin D concentrations. Lower serum 25(OH)D levels have been associated with higher cardiovascular mortality, with risk stratification as follows: <10 ng/mL = very high risk, 10–19 ng/mL = high risk, 20–29 ng/mL = moderate risk,
Arterial Blood Gas Interpretation: Explanation and Clinical Context This tool provides a structured approach to identify the primary acid base disturbance and to assess whether the observed respiratory or renal compensation is appropriate for a single predominant disorder. The algorithm first classifies the sample as acidemia or alkalemia based on pH. It then uses the relationship between pCO2 and HCO3 to identify a
BNP/Creatinine Ratio Index: Explanation and Clinical Context The BNP/Creatinine Ratio is a biomarker-based index used in patients with heart failure and renal dysfunction to assess cardiovascular risk more precisely. Elevated BNP reflects cardiac stress, whereas serum creatinine indicates renal function. Combining these parameters accounts for the confounding effect of renal impairment on BNP levels, enhancing progno
BNP/Troponin Dual Elevation Index: Explanation and Clinical Context The BNP/Troponin Dual Elevation Index is a simple clinical tool designed to stratify risk in patients with acute heart failure or suspected acute coronary syndrome by evaluating simultaneous elevations of B-type Natriuretic Peptide (BNP) and cardiac troponin. Elevated BNP (>400 pg/mL) reflects myocardial stretch and volume overload, while elevated tr
Copeptin–Troponin Composite Model: Explanation and Clinical Context The Copeptin–Troponin Composite Model refers to a dual‑biomarker approach combining measurement of copeptin (a stable surrogate marker of arginine‑vasopressin release) and high‑sensitivity cardiac troponin I (hs‑cTnI) on admission in patients with suspected acute cardiac injury or other cardiocirculatory stress. The rationale is that while troponin i
: Explanation and Clinical Context Metabolic acidosis represents a pathophysiologic condition characterized by a decrease in plasma bicarbonate concentration and a reduction in blood pH. Base excess is a key variable used in clinical practice to quantify the magnitude of metabolic acidosis and estimate the bicarbonate requirement needed for partial correction. The standard bicarbonate deficit formula incorporates bod
C-Reactive Protein / Albumin Ratio (CAR): Explanation and Clinical Context The C-Reactive Protein / Albumin Ratio (CAR) is a prognostic biomarker reflecting the balance between systemic inflammation and nutritional status. CRP is an acute-phase protein that rises in response to inflammation, whereas serum albumin decreases during systemic inflammation or malnutrition. CAR is calculated as CRP (mg/L) divided by serum
CRP/HDL Ratio (CHL Index): Explanation and Clinical Context The CRP/HDL Ratio, also known as the CHL Index, is a cardiovascular risk marker derived from the ratio of C-reactive protein (CRP) to high-density lipoprotein cholesterol (HDL-C). CRP is a marker of systemic inflammation, while HDL-C has anti-inflammatory and cardioprotective properties. A higher CHL Index indicates a greater inflammatory burden relative to
Cystatin C–NT-proBNP Combined Risk Score: Explanation and Clinical Context The Cystatin C–NT-proBNP Combined Risk Score is designed to stratify patients' cardiovascular risk by integrating renal function (Cystatin C) and cardiac stress marker (NT-proBNP). Elevated Cystatin C reflects impaired kidney function and has been associated with higher cardiovascular morbidity and mortality. NT-proBNP indicates myocardial wal
D-dimer–NT-proBNP Composite Risk Score: Explanation and Clinical Context The D-dimer–NT-proBNP Composite Risk Score is a clinical tool developed to estimate short-term adverse outcomes in patients with acute pulmonary embolism (PE). It combines plasma D-dimer levels, a marker of fibrin degradation and thrombosis activity, with NT-proBNP levels, a biomarker of myocardial stress. This composite scoring system stratifie
Derived Neutrophil-to-Lymphocyte Ratio (dNLR): Explanation and Clinical Context dNLR is calculated as the ratio of neutrophil count to the difference between total white blood cell (WBC) count and neutrophil count (dNLR = Neutrophils / [WBC - Neutrophils]). It is a simple, readily available inflammatory marker derived from routine blood counts. Elevated dNLR has been associated with adverse outcomes in patients with
Derived Neutrophil-to-Lymphocyte Ratio (dNLR): Explanation and Clinical Context dNLR is calculated as the ratio of neutrophil count to the difference between total white blood cell (WBC) count and neutrophil count (dNLR = Neutrophils / [WBC - Neutrophils]). It is a simple, readily available inflammatory marker derived from routine blood counts. Elevated dNLR has been associated with adverse outcomes in patients with
Ferritin–Transferrin Saturation Ratio (Iron Deficiency in Heart Failure): Explanation and Clinical Context The Ferritin–Transferrin Saturation (TSAT) ratio is a widely used laboratory tool to assess iron status in patients with heart failure. Ferritin reflects iron storage, whereas TSAT reflects circulating iron availability. Iron deficiency is highly prevalent in heart failure and is associated with impaired functio
Ferritin–Transferrin Saturation Ratio (Iron Deficiency in Heart Failure): Explanation and Clinical Context The Ferritin–Transferrin Saturation (TSAT) ratio is a widely used laboratory tool to assess iron status in patients with heart failure. Ferritin reflects iron storage, whereas TSAT reflects circulating iron availability. Iron deficiency is highly prevalent in heart failure and is associated with impaired functio
Galectin-3 Tertile Risk Model: Explanation and Clinical Context Galectin-3 is a biomarker associated with myocardial fibrosis, inflammation, and adverse remodeling in patients with heart failure. This risk model stratifies patients into tertiles based on circulating Galectin-3 levels to predict prognosis and risk of morbidity and mortality. Tertile 1 represents low risk (<14.1 ng/mL), Tertile 2 represents intermediat
GDF-15 Risk Index for Heart Failure Outcomes: Explanation and Clinical Context The GDF-15 Risk Index is a biomarker-based tool to estimate prognosis in patients with chronic heart failure. It combines circulating levels of growth differentiation factor-15 (GDF-15), age, NT-proBNP, and NYHA functional class to stratify patients by risk of adverse outcomes including mortality and HF hospitalization. Higher GDF-15 value
HbA1c Cardiac Event Prediction Model: Explanation and Clinical Context The HbA1c Cardiac Event Prediction Model estimates the 5-year risk of cardiovascular events based on patient age, HbA1c level, and history of cardiovascular disease. Higher HbA1c reflects poorer glycemic control and is independently associated with elevated cardiovascular risk. Age contributes linearly to risk, while a history of cardiovascular di
Hs-CRP Tertile Stratification: Explanation and Clinical Context High-sensitivity C-reactive protein (Hs-CRP) is a biomarker of systemic inflammation widely used in cardiovascular risk assessment. Tertile stratification categorizes individuals into three risk groups based on circulating Hs-CRP concentrations: Tertile 1 (<1.0 mg/L) indicates low cardiovascular risk, Tertile 2 (1.0–3.0 mg/L) indicates intermediate risk,
hs-Troponin Delta Algorithm (0/1-h and 0/2-h ESC models): Explanation and Clinical Context The high-sensitivity troponin (hs-Tn) delta algorithms are validated tools to rapidly triage patients presenting with suspected non-ST-elevation acute coronary syndrome (NSTE-ACS). The 0/1-hour algorithm uses the baseline hs-Tn level and the absolute change after 1 hour to stratify patients into 'Rule-Out', 'Rule-In', or 'Obser
LDL/ApoB Ratio: Explanation and Clinical Context The LDL/ApoB ratio is a surrogate marker for LDL particle size and atherogenicity. LDL cholesterol measures the cholesterol content within LDL particles, while ApoB counts the number of atherogenic particles. A lower LDL/ApoB ratio indicates smaller, denser LDL particles, which are more prone to penetrate the arterial wall, become oxidized, and promote atherosclerosis.
Mean Platelet Volume (MPV): Explanation and Clinical Context Mean Platelet Volume (MPV) is a measure of the average size of platelets in the blood, reflecting platelet production and activation. It is calculated using the formula: MPV (fL) = (Plateletcrit [%] × 10) / Platelet count (10^9/L). MPV is a useful biomarker in cardiovascular medicine as higher values have been associated with increased platelet reactivity a
Monocyte–Lymphocyte Ratio (MLR): Explanation and Clinical Context The Monocyte–Lymphocyte Ratio (MLR) is a simple hematological index derived from routine complete blood counts by dividing the absolute monocyte count by the absolute lymphocyte count. It has emerged as a prognostic marker in various cardiovascular and inflammatory conditions. Elevated MLR has been associated with higher systemic inflammation, increase
MR-proADM Index: Explanation and Clinical Context Midregional proadrenomedullin (MR-proADM) is a stable fragment of adrenomedullin precursor, a peptide involved in vasodilation, endothelial function, and cardiovascular homeostasis. It serves as a biomarker for cardiovascular and sepsis-related risk, reflecting disease severity and predicting adverse outcomes. Clinical studies have shown that MR-proADM levels correlat
Neutrophil–Lymphocyte Ratio (NLR): Explanation and Clinical Context The Neutrophil–Lymphocyte Ratio (NLR) is calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. It is an inexpensive and widely available marker of systemic inflammation. Elevated NLR has been associated with adverse outcomes in cardiovascular diseases, cancer, and critical illness. Cut-offs vary by clinical context, b
NT-proBNP/BNP Ratio: Explanation and Clinical Context The NT-proBNP/BNP ratio is a prognostic biomarker used in heart failure and cardiovascular risk assessment. NT-proBNP, the inactive N-terminal fragment of proBNP, and BNP, the biologically active peptide, reflect ventricular wall stress and myocardial dysfunction. Differences in clearance mechanisms and half-lives may cause discrepancies in absolute concentrations
Platelet–Lymphocyte Ratio (PLR): Explanation and Clinical Context The Platelet–Lymphocyte Ratio (PLR) is a systemic inflammatory marker calculated as the ratio of platelet count to lymphocyte count in peripheral blood. Elevated PLR reflects both an increased platelet count, often associated with pro-thrombotic and inflammatory states, and a relative lymphopenia, indicating impaired immune regulation. PLR has been stu
Potassium Requirement: Comprehensive Explanation and Clinical Context The estimation of potassium requirement is an important component of clinical decision making for patients with hypokalemia. Potassium is the predominant intracellular cation and plays a key role in membrane potential regulation, cardiac electrophysiology, skeletal muscle contraction, and acid base homeostasis. Serum potassium does not reflect tota
Procalcitonin Cardiac Sepsis Index (PCSI): Explanation and Clinical Context The Procalcitonin Cardiac Sepsis Index (PCSI) is a novel composite score designed to stratify risk in patients with suspected cardiac sepsis. It integrates three critical parameters: serum procalcitonin (PCT), a marker of systemic bacterial infection; NT-proBNP, an indicator of cardiac stress; and the Sequential Organ Failure Assessment (SOFA
RDW-CV Index: Explanation and Clinical Context The RDW-CV Index is derived from the Red Cell Distribution Width (RDW) coefficient of variation relative to Mean Corpuscular Volume (MCV). It reflects the degree of anisocytosis (variability in red blood cell size) and is increasingly recognized as a prognostic biomarker in cardiovascular diseases. Elevated RDW-CV Index has been associated with higher risk of mortality a
ST2 Biomarker Risk Tier: Explanation and Clinical Context The soluble ST2 (sST2) is a member of the interleukin-1 receptor family and acts as a biomarker of myocardial stress and fibrosis. It is a strong prognostic marker in patients with heart failure and acute coronary syndromes, independently predicting mortality and heart failure readmission. Risk tiers are generally classified based on sST2 concentration: - <35
Systemic Immune-Inflammation Index (SII): Explanation and Clinical Context The Systemic Immune-Inflammation Index (SII) is calculated as Platelets × Neutrophils / Lymphocytes, reflecting the balance between host immune and inflammatory status. Originally described by Hu et al., 2014, SII has been studied in oncology and cardiovascular settings as a prognostic marker. High SII values suggest elevated systemic inflamma
Systemic Inflammation Response Index (SIRI): Explanation and Clinical Context SIRI is a novel biomarker that quantifies systemic inflammation by integrating neutrophil, monocyte, and lymphocyte counts. It is calculated as (Neutrophil count × Monocyte count) / Lymphocyte count. This index has been studied for prognostic value in cardiovascular diseases, oncology, and sepsis. A higher SIRI reflects a greater inflammato
Triglyceride/HDL-C Ratio: Explanation and Clinical Context The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio is a widely studied marker reflecting atherogenic dyslipidemia and insulin resistance. A higher ratio is associated with increased cardiovascular risk, metabolic syndrome, and subclinical atherosclerosis. Typical thresholds categorize risk as follows: <2 = low risk, 2–4 = intermediate r
Troponin–CK-MB Concordance Index: Explanation and Clinical Context The Troponin–CK-MB Concordance Index is a predictive tool designed to assess the agreement between troponin and CK-MB levels in detecting myocardial injury. It is calculated as the ratio of troponin to the sum of troponin and CK-MB, reflecting how much troponin predominates relative to CK-MB. Higher values indicate a stronger concordance of troponin w
Uric Acid Quartile Mortality Gradient: Explanation and Clinical Context This calculator stratifies patients into quartiles based on serum uric acid (UA) levels to estimate relative mortality risk. Quartile assignment (Q1–Q4) reflects population-based thresholds commonly reported in epidemiological studies. Higher uric acid levels have been associated with increased cardiovascular and all-cause mortality. The lowest q