Parallel Increase in Urinary Excretion Rates of Immunoglobulin G, Ceruloplasmin, Transferrin, and Orosomucoid in Normoalbuminuric Type 2 Diabetic Patients
- Takuma Narita, MD,
- Hiroshi Sasaki, MD,
- Mihoko Hosoba, MD,
- Takeshi Miura, MD,
- Naomi Yoshioka, MD,
- Tsukasa Morii, MD,
- Takashi Shimotomai, MD,
- Jun Koshimura, MD,
- Hiroki Fujita, MD,
- Masafumi Kakei, MD and
- Seiki Ito, MD
- From the Department of Endocrinology, Diabetes and Geriatric Medicine, Akita University School of Medicine, Akita, Japan
- Address correspondence and reprint requests to Takuma Narita, the Department of Endocrinology, Diabetes and Geriatric Medicine, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. E-mail: narita{at}med.akita-u.ac.jp
Abstract
OBJECTIVE—Increased urinary excretions of several plasma proteins with different molecular radii <55 Å and different isoelectric points (pI), such as IgG, ceruloplasmin, transferrin, and orosomucoid, have been independently reported to precede the development of microalbuminuria in diabetic patients. We examined whether increases in urinary excretions of these proteins would be in parallel in the same patient.
RESEARCH DESIGN AND METHODS—Urinary excretion rates of proteins mentioned above in timed overnight urine samples were evaluated in 61 normoalbuminuric type 2 diabetic patients (group D) aged 40–60 years and in 17 age-matched control subjects (group C).
RESULTS—The excretion rates of these proteins were significantly higher in group D than in group C. These exhibited a strong linear correlation with each other and had a weak correlation with the excretion rate of N-acethylglucosaminidase. The excretion rate of α2-macroglobulin with large molecular radii of 88 Å was not different between groups C and D, nor did they have any correlations with the excretion rates of the other proteins. Creatinine clearance and blood pressure levels in group D were significantly higher than those in group C.
CONCLUSIONS—In normoalbuminuric diabetic patients, excretion rates of plasma proteins with molecular radii <55 Å increased in parallel with each other. In view of our previous finding that urinary excretions of these plasma proteins selectively increased in parallel with enhanced glomerular filtration rate after acute protein loading, the present finding may be explained by renal hemodynamic changes, such as increased intraglomerular hydraulic pressure.
- APL, acute protein loading
- GFR, glomerular filtration rate
- GP, intraglomerular hydraulic pressure
- NAG, N-acetylglucosaminidase
- pI, isoelectric point
- SPP, small-sized plasma proteins group
- U-glu, levels of glucosuria
Footnotes
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A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
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- Accepted January 29, 2004.
- Received September 9, 2003.
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