This report describes an interesting and unusual case of acquired HDL deficiency related to infection with babesiosis. Acquired HDL deficiency, which can be defined as low HDL in a patient with a prior history of normal levels or a patient with low HDL that returns to normal after some sort of treatment or resolution of disease, is quite rare. As described in this report, the majority of these cases are probably due to a severe systemic illness that results in a generalized disturbance of lipoprotein metabolism. High levels of IL-10, which can occur in a variety of infectious disorders, as well as some types of malignancies, such as B-cell lymphomas, has been described to be a cause of undetectable HDL-C, as well as low LDL-C. Intravenous administration of IL-10 in healthy individuals has been shown to recapitulate these lipoprotein changes.
Another cause of severe acquired HDL deficiency is from the formation of autoantibodies to apoA-I, the main protein component of HDL, or to LCAT, an HDL-associated enzyme that esterifies cholesterol. Because low HDL in these disorders typically only occurs transiently, it is usually without any clinical consequences; however, patients with low HDL due to LCAT autoantibodies can present with nephrotic syndrome. Like patients with a genetic defect in LCAT, these patients can form LpX particles, which are multilamellar phospholipid vesicles rich in free cholesterol that form when LCAT produces insufficient amounts of cholesteryl esters to fill the hydrophobic core of lipoproteins. LpX particles get trapped in the glomerulus of the kidney, where they can cause severe renal damage and proteinuria. It is important to recognize this disorder, because the renal dysfunction in these patients can be treated with steroids, which suppress the formation of autoantibodies to LCAT, resulting in the disappearance of LpX and the normalization of HDL levels.
Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article.
Authors' Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
- Received for publication July 23, 2016.
- Accepted for publication August 9, 2016.
- © 2016 American Association for Clinical Chemistry