Phospholipids

This test is a quantitative analysis of phospholipids, the major form of lipids in cell membranes. Phospholipids are involved in cellular membrane composition and permeability and help control enzyme activity within the membrane. They aid transport of fatty acids and lipids across the intestinal barrier and from the liver and other fat depots to other body tissues. Phospholipids are essential for pulmonary gas exchange.

Purpose

• To aid in the evaluation of fat metabolism
• To aid diagnosis of hypothyroidism, diabetes mellitus, nephrotic syndrome, chronic pancreatitis, obstructive jaundice, and hypolipoproteinemia

Patient preparation

• Explain to the patient that this test is used to determine how the body metabolizes fats.
• Tell him that the test requires a blood sample. Explain who will perform the venipuncture and when.
• Explain that he may experience slight discomfort from the needle puncture and the tourniquet but that collecting the sample usually takes less than 3 minutes.
• Instruct him to abstain from drinking alcohol for 24 hours before the test and not to eat or drink anything after midnight before the test.
• Tell the patient to withhold or discontinue medications that may alter test results, such as antilipemics, estrogens, epinephrine, and phenothiazines, as ordered.

Procedure and posttest care

• Perform a venipuncture, and collect the sample in a 10- to 15-ml red-top tube.
• If a hematoma develops at the venipuncture site, apply warm soaks.
• Tell the patient that he may resume his usual diet.
• Resume administration of medications discontinued before the test.

Precautions

Send the sample to the laboratory immediately because spontaneous redistribution may occur among plasma lipids.

Reference values

Normal phospholipid levels range from 180 to 320 mg/dl. Although men usually have higher levels than women, values in pregnant women exceed those of men.

Abnormal findings

Elevated phospholipid levels may indicate hypothyroidism, diabetes mellitus, nephrotic syndrome, chronic pancreatitis, or obstructive jaundice. Decreased levels may indicate primary hypolipoproteinemia.

Lack of phospholipids in premature infants leads to neonatal respiratory distress syndrome.

Interfering factors

• Failure to observe pretest restrictions
• Failure to send the sample to the laboratory immediately
• Clofibrate and other antilipemics (possible decrease)
• Estrogens, epinephrine, and some phenothiazines (increase)