Hyperlipidemias Flashcards
Primary causes of hyperlipidemia
familial dyslipidemia syndrome
types IIa, IIb, and IV account for >80% of all familial dyslipidemias
Hyperlipidemia basics
modifiable risk factor for coronary artery disease!
causes accelerated atherosclerosis
Secondary causes of hyperlipidemia
- endocrine disorders: hypothyroidism, diabetes mellitus, Cushing’s syndrome
- renal disorders: nephrotic syndrome, uremia
- chronic liver disease
- medications: glucocorticoids, estrogen, thiazide diuretics, beta blockers
- pregnancy
Clinical pearl: Risk factors for coronary artery disease in evaluation of patients with hyperlipidemia
(p. 433)
current cigarette smoking (dose-dependent risk), hypertension, diabetes mellitus, low HDL cholesterol (60 mg/dL) is negative risk factor (subtract 1 from total), age (male:>45 years, female: >55 years), male gender (if you count this as risk factor do not count age), family hx of premature CAD (MI/sudden death in male first degree relative <65 yo)
Dietary risk factors for hyperlipidemia
saturated fatty acids and cholesterol –> elevation in LDL + total cholesterol
high-calorie diets do not increase LDL or cholesterol levels (are “neutral”) but do increase triglyceride levels
alcohol –> increase triglyceride levels but does not affect total cholesterol levels
Risk factors for hyperlipidemia
- diet
- age (cholesterol levels increase with age until about 65 yrs;
greatest increase in early adulthood 2 mg/dL per yr) - inactive lifestyle, abdominal obesity
- family hx hyperlipidemia
- gender (men generally > cholesterol levels than women); when women reach menopause cholesterol levels equalize (and may be higher in women)
- medications: thiazides (increase LDL, total cholesterol, triglycerides (VLDL levels); beta blockers (propanolol-increases triglycerides (VLDL) and lower HDL levels); estrogens (triglyceride levels may further increase in patients with hypertriglyceridemia); corticosteroids and HIV protease inhibitors can elevate serum lipids
- genetic mutations that predispose to most severe hyperlipidemias
- secondary causes of dyslipidemia
LDL cholesterol and CAD risk
accounts for 2/3 of total cholesterol
CAD risk primarily due to LDL component bc LDL thought to be the most atherogenic of all lipoproteins
Levels > 160 mg/dL significantly increase CAD risk
–> LDL cholesterol not directly measured but calculated:
LDL = total cholesterol - HDL - TG/5
Threshold levels for hyperlipidemia: total cholesterol
all in mg/dL:
ideal: 240
remember: total cholesterol will be higher than LDL!
Threshold levels for hyperlipidemia (LDL)
all in mg/dL:
ideal: 160
Threshold levels for hyperlipidemia (triglycerides)
for Triglycerides high level is Two Times low level
“T”
all in mg/dL:
ideal: 250
uncertain whether lowering triglyceride levels reduces coronary risk
HDL cholesterol
- protective effect (removes excess cholesterol from arterial walls) at least as strong as atherogenic effect of LDL
- for every 10 mg/dL increase in HDL level, CAD risk decreases by 50%
Low HDL ( 60 mg/dL) = “negative” risk factor (counteracts one risk factor)
Total cholesterol to HDL ratio
average/standard risk: 5.0
desirable: <4.5
LDL levels in diabetic patients
goal for LDL in diabetic patient: 100 mg/dL or lower
all diabetics with LDL > 100 mg/dL should be started on statin
if patient has CAD and diabetes mellitus: goal for LDL is 70 mg/dL or less
Clinical features hyperlipidemia
most patients asymptomatic
if severe, may see:
- Xanthelasma: yellow plaques on eyelids
- Xanthoma: hard, yellowish masses found on tendons (finger extensors, Achilles’ tendon, plantar tendons)
- Pancreatitis can occur with severe hypertriglyceridemia
Diagnosis of Hyperlipidemia
- lipid screening
- measure total cholesterol and HDL levels (nonfasting ok)
- -> if either abnormal, order full fasting lipid profile - full fasting lipid profile: triglyceride levels + calculation of LDL levels
- consider checking laboratory tests to exclude secondary causes of hyperlipidemia:
a. TSH (hypothyroidism)
b. LFTs (chronic liver disease)
c. BUN and Cr, urinary proteins (nephrotic syndrome)
d. glucose levels (diabetes)