Frequently Asked Questions about Feline Hyperlipidemia

Q

A

What causes serum to be turbid?

Elevated serum triglyceride carried by lipoproteins causes serum to appear turbid. Opacity is seen when triglyceride concentration approaches 600 mg/dL (6.8 mmol/L). Serum may have the appearance of whole milk when triglyceride concentrations reach 2500 - 4000 mg/dL (28.2 - 45.2 mmol/L).

What conditions cause hyperlipidemia?

The most common cause is a non-fasted animal. If fasting for greater than 12 hours is confirmed, then primary hyperlipidemia, or secondary hyperlipidemia due to hypothyroidism, pancreatitis, diabetes mellitus, hyperadrenocorticism, cholestasis, or nephrotic syndrome may be present.

Are high fat diets harmful to cats?

Not usually. Lipid metabolism in cats is very different from that in humans. Cats carry most of their cholesterol in HDL, and are very resistant to the development of atherosclerosis. However, if certain diseases such as hypothyroidism or diabetes mellitus are present, high fat diets could result in further lipid abnormalities. In addition, high fat diets for neutered and sedentary cats can contribute to obesity with subsequent health issues.

What causes a "cream layer’"to separate in some turbid serum samples?

The "cream layer" which floats to the top of serum is due to the presence of chylomicrons. This is normal in a non-fasted animal, but represents an abnormality if the animal has been fasted for greater than 12 hours.

Do cats develop atherosclerosis?

Contrary to humans, cats rarely develop atherosclerosis due to differences in lipid metabolism. Atherosclerosis could develop in some cats that have a concurrent disease that causes chronic hyperlipidemia.

Should persistent fasting hyperlipidemia be treated?

Yes. If the hyperlipidemia is due to a secondary cause, then treatment of the underlying condition may resolve the hyperlipidemia. There is evidence suggesting that chronic hyperlipidemia may lead to the development of pancreatitis, insulin resistance, diabetes mellitus, or atherosclerosis in some cats.