A 52-year-old man from Delhi presents with recurrent episodes of acute pancreatitis over the past 6 months. His fasting triglycerides are 1200 mg/dL (normal <150), total cholesterol 380 mg/dL, HDL 28 mg/dL, and LDL cannot be calculated. Lipid electrophoresis shows a prominent chylomicron band. He denies alcohol use and has no history of gallstones. His father died of myocardial infarction at age 48. What is the most likely diagnosis?

Explanation

## Clinical Presentation Analysis **Key Point:** Type V hyperlipoproteinemia (mixed hyperlipoproteinemia) is characterized by elevation of both chylomicrons and VLDL, resulting in severe hypertriglyceridemia (often >1000 mg/dL) with eruptive xanthomas and recurrent acute pancreatitis. ### Diagnostic Criteria for Type V | Feature | Type V | Type III | Type IV | |---------|--------|---------|--------| | **Chylomicrons present** | Yes | No | No | | **VLDL elevated** | Yes | Yes | Yes | | **Triglycerides** | >1000 mg/dL | 250–500 mg/dL | 250–500 mg/dL | | **Cholesterol** | Moderately elevated | Elevated | Normal/mildly elevated | | **HDL** | Reduced | Reduced | Reduced | | **Lipid electrophoresis** | Chylomicrons + VLDL band | Broad β band | VLDL band | | **Pancreatitis risk** | Very high | Moderate | Moderate | ### Pathophysiology **High-Yield:** Type V results from a combination of: 1. Impaired clearance of chylomicrons (lipoprotein lipase deficiency or apoC-II deficiency) 2. Overproduction of VLDL (hepatic lipid overload) 3. Often triggered by secondary factors: obesity, diabetes, alcohol, estrogens The presence of **persistent fasting chylomicrons** (normally cleared within 12 hours) is the hallmark finding that distinguishes Type V from Type IV. ### Why This Patient Has Type V 1. **Fasting chylomicron band** — diagnostic of impaired chylomicron clearance 2. **Severe hypertriglyceridemia (1200 mg/dL)** — typical of Type V 3. **Recurrent acute pancreatitis** — triglycerides >1000 mg/dL cause pancreatic inflammation via free fatty acid release 4. **Reduced HDL (28 mg/dL)** — inverse relationship with triglycerides 5. **Uncalculable LDL** — when triglycerides >400 mg/dL, Friedewald formula fails ### Management Approach ```mermaid flowchart TD A[Type V Hyperlipoproteinemia]:::outcome --> B[Acute management]:::action B --> C[Plasma exchange if pancreatitis]:::action B --> D[Fibrates + Omega-3 fatty acids]:::action A --> E[Secondary cause screening]:::decision E -->|Hypothyroidism| F[Thyroid replacement]:::action E -->|Diabetes| G[Glycemic control]:::action E -->|Obesity| H[Weight reduction]:::action A --> I[Genetic counseling]:::action ``` **Clinical Pearl:** Plasma exchange is the emergency treatment for Type V with acute pancreatitis, as it rapidly reduces triglycerides by removing chylomicrons and VLDL. **Mnemonic — Type V Features: CHOP** - **C**hylomicrons present (fasting) - **H**ypertriglyceridemia (>1000) - **O**besity and secondary factors common - **P**ancreatitis (eruptive, recurrent) [cite:Robbins 10e Ch 5]