Reference distributions for alpha₂‐macroglobulin: A practical, simple and clinically relevant approach in a large cohort

Abstract

In this 11th article in a series, reference values of serum levels alpha(2)-macroglobulin alpha(2)M) are examined. The study is based on a cohort of 40,420 Caucasian individuals from northern New England that were tested in our laboratory between 1994 and 2000. Measurements were standardized against Certified Reference Material (CRM 470)/Reference Preparation for Proteins in Human Serum (RPPHS) and the results analyzed using a previously described statistical approach. Individuals with unequivocal laboratory evidence of inflammation (C-reactive protein >10 mg/L) were excluded in one leg of the study and included in the other, confirming that alpha(2)M does not respond to acute phase drive in man. Nephrotic syndrome, diabetes mellitus, and chronic liver disease have significant effect on levels of alpha(2)M. Dramatic changes occur during life with males higher from birth to age 12, females thereafter have higher values until the ninth decade. When values were expressed as multiples of the age- and gender-specific median levels, the resulting distributions fitted a log-Gaussian distribution well over a broad range. When patient data are normalized in this manner, the distribution parameters can be used to assign a centile corresponding to an individual's measurement thus simplifying interpretation.

α2-Macroglobulin is a potential facilitator of prion protein transformation

“…The stoichiometry of hrPrP, RNA and a2M had a dramatic effect on the structures of the complexes formed and may have biological significance as plasma levels of a2M vary with age, sex and disease [19]. Co-incubation of hrPrP, RNA and a2M led to the formation of aggregates containing fibril-like structures and consistent with an amyloid-like structure when stained with Congo red.…”

“…Discussion a2M, a component of blood [19] and CSF [14], and PrP, a cell surface protein of neurons [20], lymphocytes [21] and endothelial cells [22] are able to interact in a biological context. Biological interaction between cationic PrP and anionic a2M is supported by co-immunoprecipitation results from brain homogenate.…”

Prediction for steatosis in type-2 diabetes: clinico-biological markers versus 1H-MR spectroscopy

“…Other biochemical parameters like haptoglobin which decreases in cases of intra-vascular haemolysis and increases in inflammatory states, may vary. α2-macroglobulin increases in cases of inflammation or nephrotic syndrome [35]. Taking all these data collectively, the discrimination ability of the SteatoTest in our population is not surprising.…”

Apheresis for idiopathic sudden hearing loss: Reviewing the evidence

“…Fibrinogen levels correlate with total cholesterol and LDL-cholesterol as well as with age [26]. A study investigating a-2-macroglobulin levels in a large group (n = 40,420) reported a steady increase after the age of 45, with females having constantly higher mean a-2-macroglobulin levels [27]. A review of the available literature came to very similar findings, reporting an increase in a-2-macroglobulin levels after the age of 40-50, with constantly higher mean values for females [28].…”