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A High LDL with Normal Triglycerides and HDL

By the Prismo editorial team Medically reviewed by Dr. Jonathan Reynolds Reviewed 24 August 2026 4 min read

An LDL raised by itself, while triglycerides and HDL sit where they should, is a different situation from the metabolic pattern where everything moves together. There is no insulin resistance to explain it, which shifts attention toward diet, thyroid function, and how the LDL compares with the rest of your family. The higher it is and the younger you are, the more that last question matters.

The pattern on your report

  • LDL High · moderate Key
  • Triglycerides Normal Key
  • HDL Normal Key
  • Total cholesterol High Supporting

Printed as: HDL in mmol/Lor mg/dLLDL in mmol/Lor mg/dL— About 3.0 mmol/L to 116 mg/dL.Total cholesterol in mmol/Lor mg/dLTriglycerides in mmol/Lor mg/dL

Why the numbers look like this

LDL is cleared from the blood by receptors on liver cells that pull the particles in and recycle them. How high your LDL runs depends mostly on how many of those receptors you have working and how hard the liver is being pushed to make cholesterol in the first place.

Saturated fat raises LDL primarily by reducing receptor activity. Thyroid hormone increases receptor numbers, which is why an underactive thyroid raises LDL and why treating it can bring the lipids back on its own.

And a substantial minority of isolated high LDL is inherited: a fault in the receptor gene or the proteins that work with it, present from birth, producing a lifetime of raised exposure instead of a middle-aged development. That distinction matters because risk from LDL accumulates with time as well as level.

Not being flagged is not the same as normal

NICE gives two figures worth knowing. A total cholesterol above 9.0 mmol/L, or a non-HDL above 7.5, warrants specialist assessment. And familial hypercholesterolemia should be considered in an adult with a total cholesterol above 7.5 mmol/L, or a personal or family history of premature coronary heart disease; the same guidance uses 9.0 as the search threshold in people aged 30 and over. Those are prompts to look further, not diagnoses in themselves.

What else on the report can hide this

TSH belongs on the first request, not the second. An underactive thyroid is a common, correctable cause of an isolated LDL rise, and starting a statin without checking it treats a symptom while leaving the cause running.

Family history carries as much weight as the number, and taking it costs nothing. Early heart disease in a parent or sibling, or relatives with cholesterol in the same range, changes the interpretation from a dietary observation to an inherited pattern. Physical signs support it: tendon thickening at the Achilles, or deposits around the cornea in someone young.

Lp(a) is worth measuring once here, because part of a stubbornly high LDL can be Lp(a) cholesterol, and it carries risk that no LDL target accounts for.

What usually causes it

Listed from most to least common — not from most to least serious.

  1. Very common

    Dietary saturated fat with genetic susceptibility

    The usual combination. Diet contributes, but how much your LDL responds to it is largely inherited, which is why two people eating the same way land in different places.

  2. Common

    Familial hypercholesterolemia

    Affects roughly one in two hundred and fifty people and is mostly undiagnosed. Suspected from the level, from early heart disease in the family, and from tendon signs. It is the diagnosis this pattern exists to catch.

  3. Common

    Hypothyroidism

    Reduces LDL receptor activity. Correctable, and worth excluding before committing to lifelong lipid treatment.

  4. Common

    The menopause — in the menopausal transition

    LDL rises across the transition independently of any change in diet or weight, which is often attributed to something the person did.

  5. Uncommon

    Medications

    Ciclosporin, some antiretrovirals, thiazides and corticosteroids raise LDL. Timing against the drug identifies it.

  6. Uncommon

    Nephrotic syndrome

    Heavy urinary protein loss drives cholesterol production sharply. A low albumin and frothy urine, and a urine ACR finds it.

  7. Rare

    Cholestatic liver disease

    Raises LDL substantially, with a cholestatic liver panel alongside. The lipid finding is downstream of the liver.

What is usually checked next

  • TSH Excludes a correctable cause before lifelong treatment is considered, and it should come before rather than after.
  • A family history of cholesterol levels and early heart disease The single most informative thing here, and it needs no laboratory. Early events in first-degree relatives change the whole interpretation.
  • Lp(a), measured once Part of a stubbornly high LDL can be Lp(a) cholesterol, and it adds risk that LDL targets do not capture.
  • Urine ACR, liver panel and glucose Covers the secondary causes: protein loss, cholestasis, and the metabolic contribution.
  • Genetic testing for familial hypercholesterolemia Confirms the diagnosis where suspicion is high, and enables cascade testing of relatives, which is where most of the benefit lies.

When to seek care sooner

  • Same day Chest pain or tightness on exertion
  • Soon A total cholesterol above 9.0 mmol/L, or a non-HDL above 7.5
  • Soon A parent or sibling who had a heart attack or stroke before 60
  • Soon Thickened Achilles tendons, or lumps on the knuckles or elbows
  • Soon A pale ring around the colored part of the eye before the age of 45

Questions worth bringing to your appointment

  1. Has my thyroid been checked before we discuss treatment?
  2. Given my level and my family history, should familial hypercholesterolemia be considered?
  3. Does my total or non-HDL reach the threshold for specialist assessment?
  4. Should I have Lp(a) measured once?
  5. If this is inherited, do my parents, siblings and children need testing?

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