Hyperlipidemia (Dyslipidemia)

A 52 year old male with obesity, hypertension, and type 2 diabetes mellitus presents for routine evaluation. Laboratory investigations reveal total cholesterol of 290 mg/dL, LDL cholesterol of 195 mg/dL, triglycerides of 240 mg/dL, and HDL cholesterol of 34 mg/dL. Physical examination demonstrates tendon xanthomas over the Achilles tendon. Family history is significant for premature myocardial infarction in his father at age 45 years. Diagnosis?

Diagnosis is severe hypercholesterolemia, likely familial hypercholesterolemia (FH).

1. Definition

Hyperlipidemia refers to abnormal elevation of plasma lipids or lipoproteins, including increased LDL cholesterol, triglycerides, non-HDL cholesterol, apolipoprotein B (ApoB), and/or lipoprotein(a) [Lp(a)], or reduced HDL cholesterol. Dyslipidemia is a major risk factor for atherosclerotic cardiovascular disease (ASCVD), including coronary artery disease, ischemic stroke, and peripheral arterial disease.

Hyperlipidemia is characterized by abnormal elevation of:

1. LDL cholesterol (LDL-C)
2. Triglycerides (TG)
3. Non-HDL cholesterol
4. ApoB-containing lipoproteins
5. Lipoprotein(a) [Lp(a)]

or reduction in:

1. HDL cholesterol (HDL-C)

Dyslipidemia includes:

1. Hypercholesterolemia
2. Hypertriglyceridemia
3. Mixed dyslipidemia
4. Elevated Lp(a)

2. Lipoprotein Physiology

Chylomicrons

1. Transport dietary triglycerides
2. Synthesized in intestine
3. Contain ApoB-48

VLDL

1. Transport endogenous triglycerides
2. Produced by liver
3. Contain ApoB-100

LDL

1. Deliver cholesterol to peripheral tissues
2. Major atherogenic lipoprotein
3. Elevated LDL strongly associated with ASCVD

HDL

1. Mediates reverse cholesterol transport
2. Low HDL is associated with increased ASCVD risk

3. Classification

3.1 Primary (Genetic) Dyslipidemia

Familial Hypercholesterolemia (FH)

1. Most commonly due to LDL receptor mutation (~85–90%)
2. Markedly elevated LDL cholesterol
3. Tendon xanthomas
4. Premature ASCVD
5. Heterozygous FH occurs in approximately 1 in 250–300 individuals

Familial Combined Hyperlipidemia

1. Elevated LDL and triglycerides
2. Increased ApoB levels
3. Common inherited dyslipidemia

Familial Hypertriglyceridemia

1. Elevated triglycerides
2. Increased pancreatitis risk

Familial Chylomicronemia Syndrome

1. Severe hypertriglyceridemia
2. Recurrent pancreatitis
3. Lipoprotein lipase pathway defects

3.2 Secondary Dyslipidemia

Endocrine Causes

1. Diabetes mellitus
2. Hypothyroidism
3. Cushing syndrome

Renal Causes

1. Nephrotic syndrome
2. Chronic kidney disease

Hepatic Causes

1. Cholestatic liver disease

Lifestyle Causes

1. Obesity
2. Sedentary lifestyle
3. Alcohol use
4. Diet high in saturated fats

Drug Causes

1. Corticosteroids
2. Thiazide diuretics
3. Beta-blockers
4. Retinoids
5. Protease inhibitors

4. Pathophysiology

1. ApoB-containing lipoproteins promote atherosclerosis
2. Oxidized LDL causes endothelial dysfunction and foam cell formation
3. Progressive plaque formation leads to ASCVD
4. Severe hypertriglyceridemia predisposes to acute pancreatitis
5. Low HDL impairs reverse cholesterol transport

5. Clinical Features

Most patients are asymptomatic until complications develop

Physical Findings

Xanthelasma

1. Yellow cholesterol-rich plaques around eyelids

Tendon Xanthomas

1. Strongly suggest familial hypercholesterolemia
2. Commonly involve Achilles and extensor tendons

Eruptive Xanthomas

1. Associated with severe hypertriglyceridemia
2. Small yellow papules over extensor surfaces

Lipemia Retinalis

1. Milky retinal vessels in severe hypertriglyceridemia

6. Complications

Atherosclerotic Cardiovascular Disease (ASCVD)

1. Coronary artery disease
2. Myocardial infarction
3. Ischemic stroke
4. Peripheral arterial disease

Acute Pancreatitis

1. Risk increases significantly when triglycerides ≥500 mg/dL
2. Risk is particularly high when triglycerides ≥1000 mg/dL

7. Diagnosis

7.1 Lipid Profile

Measures:

1. Total cholesterol
2. LDL cholesterol
3. HDL cholesterol
4. Triglycerides
5. Non-HDL cholesterol

Current guidelines prefer use of:

1. Martin/Hopkins equation
2. Sampson/NIH equation

over Friedewald equation for LDL estimation

7.2 ApoB Measurement

ApoB better reflects total atherogenic particle burden and is useful in:

1. Elevated triglycerides
2. Diabetes mellitus
3. Low achieved LDL-C
4. Residual ASCVD risk assessment

7.3 Lipoprotein(a) [Lp(a)]

1. Should be measured at least once in all adults
2. Elevated Lp(a) is a major ASCVD risk-enhancing factor

Elevated levels:

1. ≥50 mg/dL or ≥125 nmol/L increase ASCVD risk

7.4 Evaluation for Secondary Causes

1. TSH for hypothyroidism
2. HbA1c or fasting glucose for diabetes mellitus
3. Liver function tests
4. Renal function tests
5. Urinalysis for nephrotic syndrome

8. Severe Hypercholesterolemia / Familial Hypercholesterolemia

Suspect FH in:

1. LDL ≥190 mg/dL
2. Tendon xanthomas
3. Premature ASCVD
4. Strong family history

Genetic Defects

1. LDL receptor mutation
2. ApoB mutation
3. PCSK9 gain-of-function mutation

Panel-based genetic testing may help confirm FH and identify higher ASCVD risk patients

9. Management

9.1 Lifestyle Modification

1. Weight reduction
2. Regular aerobic exercise
3. Smoking cessation
4. Reduced saturated and trans fat intake
5. Increased dietary fiber
6. Limit alcohol intake

Lifestyle optimization should begin early to reduce cumulative exposure to atherogenic lipoproteins

9.2 Statins (First-Line Therapy)

Mechanism:

1. HMG-CoA reductase inhibition
2. Increased hepatic LDL receptor expression
3. Reduced LDL cholesterol

High-Intensity Statins

1. Atorvastatin
2. Rosuvastatin

Indications

1. Clinical ASCVD
2. LDL ≥190 mg/dL
3. Diabetes mellitus age 40–75 years
4. Elevated ASCVD risk

LDL Goals

Primary Prevention High Risk

1. LDL goal <70 mg/dL
2. Non-HDL goal <100 mg/dL

Secondary Prevention / Very High Risk ASCVD

1. LDL goal <55 mg/dL
2. Non-HDL goal <85 mg/dL

9.3 Ezetimibe

1. Inhibits intestinal cholesterol absorption
2. Added if LDL goals are not achieved with statins

9.4 PCSK9 Inhibitors

1. Evolocumab
2. Alirocumab

Used in:

1. Familial hypercholesterolemia
2. Very high-risk ASCVD
3. Persistent LDL elevation despite statin therapy

9.5 Inclisiran

1. Small interfering RNA against PCSK9
2. Used in persistent LDL elevation despite maximally tolerated therapy

9.6 Bempedoic Acid

1. ATP citrate lyase inhibitor
2. Useful in statin intolerance or for additional LDL lowering

9.7 Fibrates

1. Fenofibrate
2. Gemfibrozil

Primarily lower triglycerides and reduce pancreatitis risk

9.8 Omega-3 Fatty Acids / Icosapent Ethyl

1. Lower triglycerides
2. Reduce ASCVD risk in selected high-risk patients

10. Statin Adverse Effects

1. Myalgia
2. Myopathy
3. Rare rhabdomyolysis
4. Elevated liver enzymes
5. Mild increase in diabetes risk

True statin intolerance is less common than perceived

11. Monitoring

1. Repeat lipid profile after therapy initiation
2. Monitor adherence and lifestyle changes
3. CK only if muscle symptoms occur
4. Liver enzymes only if clinically indicated

12. Prognosis

1. Early lipid lowering significantly reduces ASCVD risk
2. Untreated familial hypercholesterolemia markedly increases premature cardiovascular disease risk

13. Key Clinical Insight

Patient with markedly elevated LDL cholesterol, tendon xanthomas, and premature family history of myocardial infarction strongly suggests familial hypercholesterolemia

14. Key Exam Points

1. LDL is the primary atherogenic lipoprotein
2. ApoB-containing lipoproteins drive ASCVD risk
3. Familial hypercholesterolemia is most commonly due to LDL receptor mutation
4. Tendon xanthomas strongly suggest familial hypercholesterolemia
5. Severe hypertriglyceridemia markedly increases pancreatitis risk
6. Statins are first-line therapy for elevated LDL cholesterol
7. PCSK9 inhibitors and inclisiran are used for persistent LDL elevation
8. Lp(a) should be measured at least once in all adults
9. LDL ≥190 mg/dL strongly suggests severe hypercholesterolemia/FH
10. Early aggressive lipid lowering reduces cardiovascular morbidity and mortality

Chronic Liver Disease (CLD)

A 56 year old male with a history of long-term alcohol use presents with progressive abdominal distension, lower limb edema, fatigue, and confusion. Physical examination reveals jaundice, spider angiomas, ascites with shifting dullness, and asterixis. Laboratory investigations show elevated bilirubin, prolonged INR, low albumin, and thrombocytopenia. Ultrasound demonstrates a nodular liver with splenomegaly and ascites. Diagnosis?

Diagnosis is decompensated cirrhosis due to chronic liver disease.

1. Definition

Chronic liver disease is progressive liver injury lasting >6 months resulting in fibrosis and eventual cirrhosis.

Cirrhosis is characterized by:

1. Irreversible fibrosis
2. Regenerative nodules
3. Distorted hepatic architecture

Compensated cirrhosis may have normal or mildly abnormal liver enzymes.

2. Etiology

2.1 Common Causes

1. Alcohol-associated liver disease
2. Metabolic dysfunction associated steatotic liver disease (MASLD/MASH)
3. Chronic hepatitis B
4. Chronic hepatitis C

Alcohol-associated liver disease is one of the most common causes of cirrhosis worldwide

2.2 Other Causes

1. Autoimmune hepatitis
2. Hemochromatosis
3. Wilson disease
4. Alpha-1 antitrypsin deficiency
5. Primary biliary cholangitis (PBC)
6. Primary sclerosing cholangitis (PSC)
7. Budd-Chiari syndrome

3. Pathophysiology

1. Chronic hepatic injury activates stellate cells
2. Excess collagen deposition causes fibrosis
3. Distortion of hepatic vascular architecture develops
4. Increased intrahepatic resistance causes portal hypertension
5. Progressive synthetic dysfunction leads to cirrhosis

4. Compensated vs Decompensated Cirrhosis

Compensated Cirrhosis

1. Often asymptomatic
2. May have normal liver enzymes
3. Preserved hepatic function

Decompensated Cirrhosis

1. Ascites
2. Variceal hemorrhage
3. Hepatic encephalopathy
4. Spontaneous bacterial peritonitis
5. Jaundice
6. Hepatorenal syndrome

Any decompensation warrants hepatology and transplant evaluation

5. Clinical Features

5.1 Constitutional Features

1. Fatigue
2. Weight loss
3. Weakness

5.2 Portal Hypertension Features

1. Ascites
2. Splenomegaly
3. Caput medusae
4. Esophageal varices
5. Rectal varices

Platelets <150,000 may be an early clue due to hypersplenism

5.3 Chronic Liver Disease Stigmata

1. Jaundice
2. Spider angiomas
3. Palmar erythema
4. Gynecomastia
5. Testicular atrophy
6. Muscle wasting

5.4 Hepatic Encephalopathy Features

1. Sleep reversal
2. Confusion
3. Asterixis
4. Coma

6. Diagnosis

6.1 Laboratory Findings

1. Elevated bilirubin
2. Elevated INR
3. Low albumin
4. Thrombocytopenia
5. AST and ALT may normalize in end-stage disease

Albumin and INR best reflect synthetic liver function

6.2 Etiology-Specific Evaluation

Alcohol-Associated Liver Disease

1. AST:ALT approximately 2:1
2. Elevated GGT
3. Macrocytosis
4. AST/ALT usually <500

MASLD/MASH

1. Associated with obesity and metabolic syndrome
2. ALT often exceeds AST early

Autoimmune Hepatitis

1. ANA positive
2. ASMA positive
3. Anti-LKM1 positive
4. Elevated IgG

Hemochromatosis

1. Elevated ferritin
2. Elevated transferrin saturation

Wilson Disease

1. Low ceruloplasmin
2. Elevated urine copper
3. Kayser-Fleischer rings

Primary Biliary Cholangitis

1. Antimitochondrial antibody positive
2. Elevated ALP
3. Pruritus

Primary Sclerosing Cholangitis

1. MRCP shows beading
2. Associated with ulcerative colitis
3. Increased cholangiocarcinoma risk

7. Imaging

RUQ Ultrasound with Doppler

1. Best initial imaging
2. Detects nodularity
3. Detects ascites
4. Evaluates thrombosis

Transient Elastography (FibroScan)

1. Preferred noninvasive fibrosis assessment
2. Measures liver stiffness

Liver Biopsy

1. Gold standard when diagnosis remains uncertain
2. Transjugular route preferred with coagulopathy or ascites

8. Major Complications

8.1 Ascites

Most common complication.

Diagnosis

1. New ascites requires diagnostic paracentesis
2. Perform promptly in hospitalized patients

Interpretation

1. SAAG ≥1.1 suggests portal hypertension

Treatment

1. Sodium restriction ≤2 g/day
2. Spironolactone and furosemide
3. Typical starting ratio: 100:40
4. Avoid NSAIDs and ACE inhibitors/ARBs in decompensated disease

8.2 Spontaneous Bacterial Peritonitis (SBP)

Diagnosis

1. Ascitic PMN ≥250 cells/µL

Common Organisms

1. Escherichia coli
2. Enteric gram-negative organisms

Treatment

1. Cefotaxime or ceftriaxone
2. Albumin:
• 1.5 g/kg day 1
• 1 g/kg day 3

Prophylaxis

1. TMP-SMX or fluoroquinolone in selected patients

8.3 Esophageal Varices

Acute Variceal Bleeding

1. Secure airway if indicated
2. IV access and resuscitation
3. Start octreotide immediately
4. Start ceftriaxone before endoscopy
5. Urgent upper endoscopy with endoscopic variceal ligation

Restrictive transfusion strategy with target hemoglobin approximately 7 g/dL

Prevention

Primary prophylaxis:

1. Nonselective beta blockers or endoscopic variceal ligation

Secondary prophylaxis:

1. Nonselective beta blockers plus repeated band ligation

TIPS may be required for recurrent bleeding

8.4 Hepatic Encephalopathy

Triggers

1. GI bleeding
2. Infection
3. Constipation
4. Sedatives
5. Hypokalemia
6. Metabolic alkalosis

Treatment

1. Lactulose first-line
2. Titrate to 2 to 4 soft stools daily
3. Add rifaximin for recurrent disease

Ammonia levels correlate poorly with severity

8.5 Hepatorenal Syndrome (HRS-AKI)

Diagnosis

1. AKI despite albumin challenge
2. No shock
3. No nephrotoxins
4. No structural kidney disease

Treatment

1. Albumin
2. Terlipressin preferred where available
3. Norepinephrine in ICU setting
4. Liver transplantation is definitive

9. Hepatocellular Carcinoma (HCC)

Surveillance

1. Liver ultrasound with or without AFP every 6 months
2. AFP alone is insufficient

Continue surveillance even after HCV cure if cirrhosis remains

Diagnosis

1. Multiphasic CT or MRI
2. Arterial enhancement with venous washout

Biopsy is not always required

10. Severity Assessment

Child-Pugh Score

Includes:

1. Bilirubin
2. Albumin
3. INR/PT
4. Ascites
5. Encephalopathy

Class A = compensated disease
Class C = severe disease

MELD-Na Score

Uses:

1. Bilirubin
2. INR
3. Creatinine
4. Sodium

MELD ≥15 warrants transplant evaluation

11. Management

1. Treat underlying cause
2. Avoid alcohol
3. Vaccinate against HAV, HBV, influenza, pneumococcus, and COVID
4. Maintain adequate nutrition with protein intake 1.2–1.5 g/kg/day
5. Avoid NSAIDs, aminoglycosides, and excessive sedatives
6. Acetaminophen may be used cautiously, often ≤2 g/day
7. Early transplant referral when indicated

Routine protein restriction is not recommended

12. Transplant Indications

1. MELD ≥15
2. Decompensated cirrhosis
3. Hepatocellular carcinoma within transplant criteria
4. Hepatorenal syndrome
5. Hepatopulmonary syndrome

Definitive treatment for end-stage cirrhosis is liver transplantation

13. Key Clinical Insight

Patient with ascites, thrombocytopenia, jaundice, encephalopathy, and signs of portal hypertension strongly suggests decompensated cirrhosis

14. Key Exam Points

1. Most common complication is ascites
2. Most dangerous acute complication is variceal hemorrhage
3. New ascites requires diagnostic paracentesis
4. Lactulose is first-line for hepatic encephalopathy
5. SBP is diagnosed with PMN ≥250 cells/µL
6. Ultrasound with or without AFP every 6 months for HCC surveillance
7. MELD-Na guides transplant allocation
8. Protein restriction is outdated and not routinely recommended
9. Cirrhosis may have normal AST/ALT in late disease
10. Liver transplantation is definitive treatment for end-stage cirrhosis