Hypolipoproteinemia

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Overview

Causes

Classification

Abetalipoproteinemia
Hypobetalipoproteinemia
Familial hypoalphalipoproteinemia
LCAT Deficiency
Chylomicron retention disease
Tangier disease
Familial combined hypolipidemia

Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohamed Moubarak, M.D. [2]; Aravind Kuchkuntla, M.B.B.S[3]; Tarek Nafee, M.D. [4]

Synonyms and keywords: Hypolipidemia, low lipoprotein

Overview

Hypolipoproteinemia is defined as low levels of one or more type of lipoproteins. Hypolipidemia, a commonly used term in the clinical practice, describes low level of lipids, whether cholesterol or triglycerides. They are referred to as hypocholesterolemia and hypotriglyceridemia respectively. Despite being commonly used to describe abnormalities in lipid metabolism, the term hypolipidemia is not very specific. For instance, people who have metabolic syndrome have high LDL and low HDL and yet they are described to have hyperlipidemia when their HDL level is decreased. Moreover, some people who have low levels of a specific lipoprotein may have a normal measured total cholesterol and triglyceride levels.

Synopsis

Classification

Shown below is an algorithm depicting the classification of hypolipoproteinemia into primary and secondary.

 
 
 
 
 
 
Hypolipoproteinemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Primary
(Genetic)
 
 
 
 
 
 
 
 
 
 
 
 
 
Secondary
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abetalipoproteinemia
Apolipoprotein 1 deficiency
Chylomicron retention disease
Familial combined hypolipidemia
Hypobetalipoproteinemia
LCAT deficiency
Primary alphalipoproteinemia
PCSK9 deficiency
Tangier disease
 
 
 
 
 
 
 
 
 
 
 
 
 
Anemia
Criticial illness
Chronic inflammation
Chronic liver disease
Hyperthyroidism
Infection
Malabsorption
Malignancy

Approach to Low Cholesterol Level

 
 
 
Low LDL C <5th percentile or HDL <20mg/dl
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Clinical symptoms Diarrhea±Vomiting±Failure to Thrive
 
If No, then screen for LCAT deficiency, Apo A1 deficiency, Tangier Disease or Heterozygous HBL
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
If Yes, Screen for secondary causes of low cholesterol as they are more common
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Once the secondary causes of low cholesterol are ruled out then consider screening for Abetalipoproteinemia, Chylomicron Retension Disease and Familial Combined Hypolipidemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lipid panel: Low LDL C with normal Triglyceride level
 
Suggests Chylomicron Retention Disease, confirm diagnosis by endoscopy and gene sequencing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Low LDL C with Low Triglyceride can be Abetalipoproteinemia or Homozygous hypobetalipoprotienemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Screen the lipid panel of the patient's parents
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Normal Lipid level suggests Abetalipoproteinemia, confirm diagnosis with gene sequencing
 
 
 
Lipid levels 50% of normal, it is Familial Homozygous Hypobetalipoproteinemia, confirm by gene sequencing


Low LDL C

  • It is defined as patients having LDL C less than the 5th percentile when compared to normal population.
  • We have to rule out secondary causes first and then consider screening for rare genetic diseases.
Abetalipoprotienemia Familial Homozygous

Hypobetalipoproteinemia

Familial Heterozygous

Hypobetalipoproteinemia

PCSK9 deficiency Chylomicron Retention

Disease

Familial Combined

Hypolipidemia

LDL C ↓↓↓ (0) ↓↓↓ ↓↓ ↓↓
Apo B ↓↓↓( 0) ↓↓↓ N ↓↓ N
TG ↓↓↓ ↓↓↓ N
TC ↓↓↓ ↓↓↓ ↓↓
HDL ↓↓ ↓↓ N N ↓↓ ↓↓
VLDL ↓↓ ↓↓ N ↓↓
Apo A1 ↓↓ ↓↓ N ↓↓ N


Low HDL

Familial LCAT

Deficiency

Fish Eye

Disease

Tangier Disease
Clinical Features Corneal opacities, anaemia

and progressive renal disease with proteinuria

Corneal opacities only;

Normal renal function

Characteristic Laboratory Finding

References


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