Calculadora de Colesterol LDL

Calcule seu LDL (colesterol ruim) usando a fórmula de Friedewald

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Colesterol Total TC

Normal: < 200 mg/dL

Colesterol HDL (Colesterol Bom)

Normal: ≥ 40 mg/dL

Triglicerídeos

Normal: < 150 mg/dL

Perguntas Frequentes (FAQ)

Por que o LDL é chamado de "colesterol ruim"?

O LDL é chamado de "colesterol ruim" porque: (1) Contribui para a aterosclerose ao se depositar nas paredes arteriais; (2) Desencadeia inflamação, atraindo células imunes para formar placas; (3) Causa estreitamento vascular conforme as placas crescem; (4) Pode levar à trombose quando as placas se rompem, causando ataques cardíacos ou derrames; (5) Existe uma relação dose-resposta - níveis mais altos de LDL significam maior risco cardiovascular. Em contraste, o HDL pode remover o colesterol das paredes arteriais e por isso é chamado de "colesterol bom".

Como posso baixar meu colesterol LDL?

Baixar o colesterol LDL requer manejo abrangente: Mudanças no estilo de vida: (1) Dieta: Reduzir gorduras saturadas e trans, aumentar fibra dietética; (2) Exercício: Pelo menos 150 minutos de exercício aeróbico de intensidade moderada por semana; (3) Peso: A perda de peso pode baixar o LDL; (4) Parar de fumar: Parar melhora o perfil lipídico. Medicamentos: (1) Estatinas: Fármacos de primeira linha, podem reduzir o LDL em 25-50%; (2) Ezetimiba: Terapia adjunta para maior redução do LDL; (3) Inibidores de PCSK9: Fármacos potentes para baixar lipídios; (4) Sequestrantes de ácidos biliares: Fármacos antigos para baixar lipídios. O tratamento deve ser guiado por um médico baseado no risco individual.

Quando o LDL deve ser medido diretamente em vez de usar a fórmula?

A medição direta do LDL deve ser realizada nestas situações: (1) Triglicerídeos > 400 mg/dL (4.52 mmol/L); (2) Hiperlipidemia tipo III (distribetalipoproteinemia familiar); (3) Mal estado de jejum ou estado não jejum; (4) Quando é necessária avaliação precisa do LDL (como monitoramento do tratamento); (5) Outras condições que afetam a precisão da fórmula. A medição direta do LDL (como método homogêneo ou ultracentrifugação) é mais precisa mas mais cara, não adequada para triagem rotineira.

Os testes de colesterol requerem jejum?

Tradicionalmente eram necessárias 8-12 horas de jejum antes dos testes lipídicos porque comer afeta os níveis de triglicerídeos. No entanto, as diretrizes mais recentes sugerem: (1) O teste não jejum é aceitável para triagem rotineira; (2) O cálculo do LDL pode ser menos preciso quando os triglicerídeos estão elevados em estado não jejum; (3) Os triglicerídeos aumentam significativamente em estado não jejum; (4) O colesterol total e HDL são menos afetados por comer. Recomendação: Se estiver usando a fórmula de Friedewald para calcular LDL, prefere-se teste em jejum. Se o LDL for medido diretamente, o teste não jejum também é aceitável.

Quão baixo o LDL deve ser baixado?

Os valores alvo de LDL devem ser determinados com base na estratificação do risco cardiovascular: (1) Risco muito alto: LDL < 70 mg/dL (1.81 mmol/L), ou mesmo < 55 mg/dL (1.42 mmol/L); (2) Risco alto: LDL < 100 mg/dL (2.59 mmol/L); (3) Risco moderado: LDL < 130 mg/dL (3.36 mmol/L); (4) Risco baixo: LDL < 160 mg/dL (4.14 mmol/L). "Quanto mais baixo, melhor"? Para pacientes de muito alto risco, estudos mostram que baixar o LDL para 50 mg/dL ou mesmo mais baixo é seguro e pode reduzir ainda mais o risco de eventos cardiovasculares. No entanto, os valores alvo devem ser determinados por médicos com base nas circunstâncias individuais do paciente.

Quais são as limitações da fórmula de Friedewald?

A fórmula de Friedewald tem várias limitações importantes: (1) Triglicerídeos altos: A fórmula é imprecisa quando TG > 400 mg/dL (4.52 mmol/L); (2) Hiperlipidemia tipo III: A fórmula não se aplica a estes pacientes; (3) Estado não jejum: Idealmente deve ser medido após 12 horas de jejum; (4) Natureza de estimativa: Esta é uma fórmula empírica, a medição direta é mais precisa; (5) Variação individual: A fórmula assume uma proporção fixa, mas a composição real de VLDL varia. Para decisões clínicas precisas, especialmente quando os triglicerídeos estão elevados, recomenda-se a medição direta do LDL.

Aviso Legal Médico

Esta calculadora fornece resultados apenas para referência e não pode substituir diagnóstico médico profissional. A avaliação do colesterol LDL deve ser realizada por profissionais de saúde. A calculadora usa a fórmula de Friedewald que tem limitações e pode não ser precisa para todas as pessoas. Consulte seu médico para avaliação adequada de colesterol e decisões de tratamento.

LDL cholesterol is the number most cardiovascular risk decisions are built on, yet on most lipid panels it is never measured. It is calculated from the three values the laboratory does measure: total cholesterol, HDL cholesterol and triglycerides. Understanding which equation produced your LDL matters, because the equations disagree most in exactly the situations where the result changes management, namely low LDL and high triglycerides.

A fórmula

Friedewald (mg/dL):   LDL = Total cholesterol - HDL - (Triglycerides / 5)
Friedewald (mmol/L):  LDL = Total cholesterol - HDL - (Triglycerides / 2.2)
Non-HDL cholesterol = Total cholesterol - HDL

Triglycerides / 5 estimates VLDL cholesterol in mg/dL, assuming a fixed ratio of triglyceride to cholesterol in VLDL particles
Non-HDL cholesterol needs no estimation step and stays valid at any triglyceride level

Friedewald WT, Levy RI, Fredrickson DS, Clinical Chemistry, 1972. The fixed divisor was derived from a small sample and assumes a constant VLDL composition, which is the assumption that fails at high triglycerides.

How the calculation works

Total cholesterol is distributed across three main lipoprotein classes: HDL, LDL and VLDL. Laboratories measure total cholesterol and HDL directly, and measure triglycerides, which travel mostly in VLDL. If the ratio of triglyceride to cholesterol inside VLDL particles were constant, dividing triglycerides by five would give VLDL cholesterol, and subtracting HDL and VLDL from the total would leave LDL. That is precisely what the Friedewald equation does.

The weakness is the fixed divisor. VLDL composition is not constant; it varies with triglyceride concentration and between individuals. As triglycerides rise, the ratio drifts and the divisor of five increasingly overestimates VLDL cholesterol, which makes calculated LDL too low. This is why the equation is conventionally treated as invalid above 400 mg/dL of triglycerides, and why it underestimates LDL well before that ceiling.

The Martin-Hopkins method addresses this by replacing the fixed divisor with one selected from a lookup table indexed by the person's own triglyceride and non-HDL values, derived from a very large clinical laboratory dataset. It is more accurate at low LDL and at raised triglycerides, and many laboratories have adopted it. If your report includes an LDL that differs from what the Friedewald equation gives, this is usually why.

How to read your result

The bands below come from long-standing US guidance and are useful for orientation, but current cholesterol guidelines do not treat LDL as a universal target with one cut-off. Treatment decisions depend on overall cardiovascular risk, so the same LDL can be acceptable in one person and an indication for treatment in another.

An LDL of 190 mg/dL or above in an adult is treated as a specific signal, not just a severe number: it raises the possibility of familial hypercholesterolaemia and prompts family screening.
Non-HDL cholesterol, simply total minus HDL, requires no estimation, stays valid when triglycerides are high, and is a stronger predictor of risk in people with diabetes or metabolic syndrome.

LDL cholesterol	Conventional description
Below 100 mg/dL (2.6 mmol/L)	Optimal
100 to 129 mg/dL (2.6 to 3.3 mmol/L)	Near optimal
130 to 159 mg/dL (3.4 to 4.1 mmol/L)	Borderline high
160 to 189 mg/dL (4.1 to 4.9 mmol/L)	High
190 mg/dL (4.9 mmol/L) and above	Very high, prompts assessment for familial hypercholesterolaemia

Fasting, non-fasting and why your number moves

Lipid panels were traditionally drawn fasting because triglycerides rise after a meal, and because the Friedewald equation is sensitive to triglycerides. Current guidance in both Europe and the United States accepts non-fasting samples for most routine assessment, reserving a repeat fasting sample for cases where non-fasting triglycerides come back markedly elevated.

Biological variation also matters when comparing two results. Total cholesterol commonly varies by several percent between measurements in the same stable person, and triglycerides vary considerably more. A change of a few mg/dL between two panels is usually noise rather than signal, and a treatment decision should rest on the trend across repeated measurements rather than on one reading.

Limitações

The Friedewald equation is not valid when triglycerides exceed 400 mg/dL (4.5 mmol/L), and it progressively underestimates LDL at triglyceride levels well below that ceiling.
Accuracy is worst where it matters most for treatment: at LDL below 70 mg/dL, the level many high-risk patients are treated towards, Friedewald can understate the true value substantially.
The equation is not valid in type III hyperlipoproteinaemia or when chylomicrons are present, because the assumed VLDL composition no longer holds.
Errors in any of the three measured inputs propagate directly into the calculated LDL, and each of those measurements carries its own analytical variation.
If your laboratory uses the Martin-Hopkins method or a direct LDL assay, its reported LDL will not match the Friedewald result, and the two should not be compared across time as if they were the same measurement.
LDL is one input to cardiovascular risk. Age, blood pressure, smoking, diabetes, family history and lipoprotein(a) all matter, and no single lipid value determines whether treatment is warranted.

Perguntas frequentes

Is LDL cholesterol measured or calculated?

On most standard lipid panels it is calculated, not measured, from total cholesterol, HDL and triglycerides. Direct LDL assays exist and are used when the calculation is unreliable, such as when triglycerides are very high.

Why is the Friedewald equation invalid above 400 mg/dL of triglycerides?

The equation estimates VLDL cholesterol as triglycerides divided by five, which assumes a constant composition of VLDL particles. That assumption breaks down as triglycerides rise, so above roughly 400 mg/dL the estimate is unreliable and a direct LDL measurement is used instead.

What is non-HDL cholesterol and why does it appear on my report?

Non-HDL cholesterol is total cholesterol minus HDL. It captures the cholesterol carried by all atherogenic particles, needs no estimation step, and remains valid when triglycerides are high, which makes it particularly useful in diabetes and metabolic syndrome.

Do I need to fast before a lipid panel?

Usually not. Current European and American guidance accepts non-fasting lipid panels for routine assessment, with a fasting repeat reserved for cases where non-fasting triglycerides come back markedly elevated. Follow whatever instruction the ordering clinician gives.

My LDL changed between two tests. Is that meaningful?

Often not. Cholesterol varies biologically between measurements even in a stable person, and triglycerides vary considerably more. Small differences between consecutive panels are usually variation rather than a real change; the trend across several results is what carries information.