Kidney Week

Abstract: SA-PO1044

Association Between Estimated Protein Intake and Single-Nephron Glomerular Filtration Rate in Healthy Adults

Session Information

• Diet and Nutrition: Clinical
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Health Maintenance, Nutrition, and Metabolism

• 1302 Health Maintenance, Nutrition, and Metabolism: Clinical

Authors

• Oba, Rina, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Rina Oba,

• Sasaki, Takaya, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Takaya Sasaki,

• Kanzaki, Go, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Go Kanzaki,

• Haruhara, Kotaro, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Kotaro Haruhara,

• Okabayashi, Yusuke, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Yusuke Okabayashi,

• Koike, Kentaro, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Kentaro Koike,

• Kobayashi, Akimitsu, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Akimitsu Kobayashi,

• Yamamoto, Izumi, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Izumi Yamamoto,

• Tsuboi, Nobuo, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Nobuo Tsuboi,

• Yokoo, Takashi, The Jikei University School of Medicine, Minato-ku, TOKYO, Japan

Takashi Yokoo,

Group or Team Name

• The Jikei University School of Medicine, Division of Nephrology and Hypertension, Department of Internal Medicine.

Background

High protein intake can increase renal plasma flow and glomerular filtration rate (GFR) in response to excretory overload, which may exacerbate kidney disease progression. Glomerular hypertrophy has been shown to be closely associated with sclerosis at the level of a single nephron in experimental models. However, the mechanisms by which an excessive protein diet causes glomerular hyperfiltration and increases single-nephron GFR (SNGFR) have not been fully elucidated in humans. The present study aimed to calculate SNGFR by estimating the number of nephrons in living kidney donors and to evaluate the clinicopathological findings associated with SNGFR.

Methods

We identified 33 living kidney donors with a normotensive status who underwent enhanced computed tomography (CT) and kidney biopsy at donation in the Jikei University School of Medicine Hospital from 2007 to 2017. The number of nephron was calculated according to the cortical volumes of both kidneys as assessed on CT and the 1-hour post-transplant renal biopsy-determined glomerular density. Effective renal plasma flow (ERPF) was assessed as ^99mTc-MAG3 clearance, and SNGFR was calculated as the 24-hour creatinine clearance (24hCCr) divided by the total number of non-sclerosed glomeruli. The sodium intake and protein intake of the donors were estimated through a 24-hour urine collection test.

Results

Among the 33 subjects, 13 (39.3%) were males, and the mean age was 53.7 ± 8.7 years. Additionally, the mean arterial pressure (MAP) was 84.4 ± 9.2 mmHg, and the mean 24hCCr was 112.8 ± 25.5 ml/min/1.73 m². Urinalysis findings were normal. The estimated total nephron number was 698,308 ± 218,740/kidney, and the mean SNGFR was 90.3 ± 33.7 nl/min/1.73 m². SNGFR was strongly and directly associated with the estimated sodium and protein intake (EPI) (P = 0.0365 and 0.0048, respectively) but was not associated with the donor age, BMI, MAP, ERPF, glomerulosclerosis index, or tubular injury level. Interestingly, SNGFR was only associated with EPI as assessed by multivariate analysis.

Conclusion

In healthy adults, we noted a strong positive correlation between SNGFR and EPI. Our study findings indicate that high protein intake might increase SNGFR and cause glomerular hyperfiltration.