A High LDL in Someone Under Forty
Cholesterol damages arteries in proportion to how high it is and how long it has been that way, so the same number carries more weight at thirty than at sixty. A markedly raised LDL in a young adult with no metabolic explanation is the presentation of familial hypercholesterolemia, a condition affecting roughly one person in every two hundred and fifty and diagnosed in only a small fraction of them.
The pattern on your report
- LDL High · marked Key
- Total cholesterol High · marked Key
- Triglycerides Normal Key
- HbA1c Normal Key
Printed as: HbA1c in mmol/molor %— Not a simple multiplication: (mmol/mol divided by 10.929) plus 2.15.LDL in mmol/Lor mg/dL— About 4.9 mmol/L to 190 mg/dL, which is the figure US guidance uses for the same purpose.Total cholesterol in mmol/Lor mg/dLTriglycerides in mmol/Lor mg/dL
Why the numbers look like this
Liver cells clear LDL from the blood using receptors that capture the particles and pull them inside. Familial hypercholesterolemia is a fault in that machinery, usually in the receptor gene itself, present from conception in one copy of the gene.
Because the fault has been there from birth, the exposure is cumulative in a way that a cholesterol which rose in middle age is not. Someone with untreated FH reaches by thirty the total lifetime cholesterol exposure that an average person reaches decades later, which is why events happen early and why starting treatment young matters more than the current number suggests.
It is inherited dominantly. Each parent, sibling and child of an affected person has a one in two chance of carrying the same fault, which turns one diagnosis into a family's worth of preventable disease.
Not being flagged is not the same as normal
NICE sets the level at which FH should be considered low enough that a great many people cross it, and lowers the bar further where a close relative developed heart disease young. It also uses a higher figure when searching records of people aged 30 and over. Formal diagnosis uses a scoring system that combines the LDL with family history, physical signs and genetic testing, so the cholesterol alone neither makes nor excludes the diagnosis. What the number does is decide whether to start looking.
What else on the report can hide this
Family history is the piece of information that most changes the interpretation, and it needs specifics: not whether relatives had heart trouble, but at what age. An event before 55 in a male relative or 60 in a female one carries weight that a heart attack at 80 does not.
Physical signs are worth knowing about because they are specific when present. Thickened Achilles tendons, lumps over the knuckles, and a pale ring around the cornea appearing before middle age all support the diagnosis, though their absence excludes nothing.
Secondary causes still need excluding first: thyroid function, kidney protein loss and liver cholestasis can all raise LDL substantially. And Lp(a) belongs here too, since it is inherited alongside and compounds the risk in exactly this group.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
Diet with an inherited susceptibility
Saturated fat raises LDL, and how much it raises yours is largely genetic. Distinguished from FH by the magnitude and by what happens to relatives.
- Very common
Familial hypercholesterolemia
The diagnosis this pattern exists to find. Around one in two hundred and fifty people, mostly undiagnosed, and identifiable from the level plus family history plus tendon signs.
- Common
Familial combined hyperlipidemia
Another inherited pattern, but with variable triglycerides and a picture that differs between relatives and over time. Here triglycerides are normal, which argues against it.
- Common
Hypothyroidism
Correctable, and it should be excluded before a lifelong diagnosis is attached to a young person.
- Uncommon
Pregnancy — in pregnancy
Cholesterol rises substantially and normally through pregnancy. Lipids measured then do not represent a baseline and should be repeated afterwards.
- Uncommon
Nephrotic syndrome
Marked cholesterol elevation with a low albumin and protein in the urine. Treating the kidney disease resolves the lipids.
- Uncommon
Anorexia nervosa or restrictive eating
Counterintuitively raises cholesterol. Worth knowing because the lipid result can be the finding that prompts the real conversation.
- Rare
Homozygous familial hypercholesterolemia
Both gene copies affected. Extremely high cholesterol from childhood with skin and tendon deposits, and it needs specialist treatment urgently rather than a statin and a review.
What is usually checked next
- A detailed family history with ages at which relatives had events The age matters far more than the fact. It costs nothing and it changes the diagnosis.
- TSH, urine ACR and a liver panel Excludes the secondary causes before a lifelong label is applied to a young person.
- Examination for tendon xanthomas and corneal arcus Specific when present, and it takes two minutes in a consultation.
- Genetic testing for familial hypercholesterolemia Confirms the diagnosis and, more importantly, enables cascade testing of relatives, which is where most of the benefit sits.
- Lp(a), measured once Inherited alongside and additive to the risk, and it changes how hard everything else is treated.
When to seek care sooner
- Same day Chest pain or tightness on exertion at any age
- Same day Skin deposits present since childhood
- Soon A parent or sibling who had a heart attack or stroke before 60
- Soon A total cholesterol above 9.0 mmol/L
- Soon Thickened Achilles tendons or lumps over the knuckles
- Soon A pale ring around the colored part of the eye before 45
Questions worth bringing to your appointment
- Given my age and this level, should familial hypercholesterolemia be considered?
- At what ages did my relatives have heart problems, and does that change things?
- Have thyroid, kidney and liver causes been excluded first?
- Is genetic testing appropriate, and would it help my family?
- Should I have Lp(a) measured once?