What are Phospholipids?

Phospholipids are amphipathic lipids containing:

• Glycerol backbone

• Two fatty acids

• Phosphate group

• Nitrogenous base (e.g., choline)

They are essential components of:

• Cell membranes

• Lipoproteins (HDL, LDL, VLDL)

• Lung surfactant

• Bile

Normal Serum Level

• Serum phospholipids: 150–250 mg/dL
  (May vary slightly by lab)

Clinical Significance

1️⃣ Role in Lipoprotein Metabolism

Phospholipids form part of:

• HDL

• LDL

• VLDL

They stabilize lipoprotein structure and assist in cholesterol transport.

Altered levels may be seen in:

• Hyperlipidemia

• Atherosclerosis

• Metabolic syndrome

2️⃣ Liver Disease

Since phospholipids are synthesized in the liver:

Increased in:

• Obstructive jaundice

• Biliary cirrhosis

Decreased in:

• Severe liver damage

• Hepatocellular failure

3️⃣ Nephrotic Syndrome

• Increased serum phospholipids

• Associated with hyperlipidemia

• Due to increased hepatic lipoprotein synthesis

4️⃣ Lung Maturity (Obstetrics)

Important in assessing fetal lung maturity.

The Lecithin/Sphingomyelin (L/S) ratio in amniotic fluid:

• 2 → Mature lungs

• <1.5 → Risk of respiratory distress syndrome

Lecithin (a phospholipid) increases as fetal lungs mature.

5️⃣ Bile & Gallstone Formation

Phospholipids (especially lecithin):

• Maintain cholesterol solubility in bile

• Decreased levels → cholesterol gallstones

6️⃣ Autoimmune Disorders

Antiphospholipid antibodies are seen in:

• Antiphospholipid syndrome

• Systemic lupus erythematosus

Associated with:

• Recurrent miscarriages

• Thrombosis