Serum creatinine as an indicator of lean body mass in vegetarians and omnivores

Association between more plant-based diets and 24-h urinary creatinine excretion in 98,813 Dutch females and males: a cross-sectional study

BACKGROUND

Despite the potential health benefits and environmental gains of more plant-based diets, concerns remain about the quantity and quality of plant-based protein. Sufficient dietary protein is essential to prevent muscle loss and maintain muscle mass. However, evidence regarding the relation between plant-based diets and objectively measured muscle mass is scarce.

OBJECTIVES

We investigated, cross-sectionally, the association between groups with different dietary identities and muscle mass, indicated by their 24-h urinary creatinine excretion rate (CER).

METHODS

From the baseline assessment of the Dutch Lifelines cohort 2007-2013, 59,719 females aged 42 ± 12 y and 39,094 males aged 43 ± 12 y were included in this study. Participants' CER was used to estimate total body muscle mass. Dietary identities were self-reported and categorized as vegetarian, flexitarian, other, and no dietary identity. Associations between dietary identities and CER in females and males, separately and adjusted for relevant covariates, were analyzed using linear regression modeling.

RESULTS

Individuals with dietary identities (vegetarian, flexitarian, or other diet) had a lower protein intake than those without. Vegetarians had the lowest protein intake: vegetarian females and males consumed 0.88 ± 0.27 g/kg/d and 0.94 ± 0.29 g/kg/d, whereas females and males without an explicit dietary identity consumed 1.00 ± 0.27 g/kg/d and 1.02 ± 0.29 g/kg/d. Compared with the group without an explicit dietary identity, groups with vegetarian or flexitarian dietary identities were associated with lower CER for both females {β [95% confidence interval (CI)]: -84.9 (-97.1, -72.7) for vegetarian; -32.5 (-41.7, -23.3) for flexitarian} and males [β (95% CI): -112.4 (-151.4, -73.4) for vegetarian; -26.7 (-50.5, -2.9) for flexitarian].

CONCLUSIONS

Individuals with identities favoring plant-based diets have a lower dietary protein intake and a lower CER, indicating lower total body muscle mass. When plant-based diets are being promoted, it is important to monitor and evaluate the potential public health impact on muscle mass.

Nephroprotective Effects of Cilastatin in People at Risk of Acute Kidney Injury: A Systematic Review and Meta-analysis

Rationale & Objective

Cilastatin is an inhibitor of drug metabolism in the proximal tubule that demonstrates nephroprotective effects in animals. It has been used in humans in combination with the antibiotic imipenem to block imipenem's renal metabolism. This systematic review and meta-analysis evaluated the nephroprotective effects of cilastatin in humans.

Study Design

Systematic review and meta-analysis of observational (comparative effectiveness) studies or randomized clinical trials (RCTs).

Setting & Study Populations

People of any age at risk of acute kidney injury (AKI).

Selection Criteria for Studies

We systematically searched MEDLINE, Embase, Web of Science, and the Cochrane Controlled Trials registry from database inception to November 2023 for observational studies or RCTs that compared kidney outcomes among groups treated with cilastatin, either alone or as combination imipenem-cilastatin, versus an inactive or active control group not treated with cilastatin.

Data Extraction

Two reviewers independently evaluated studies for inclusion and risk of bias.

Analytical Approach

Treatment effects were estimated using random-effects models, and heterogeneity was quantified using the I 2 statistic.

Results

We identified 10 studies (5 RCTs, n = 531 patients; 5 observational studies, n = 6,321 participants) that met the inclusion criteria, including 4 studies with comparisons to inactive controls and 6 studies with comparisons to alternate antibiotics. Based on pooled results from 7 studies, the risk of AKI was lower with imipenem-cilastatin (risk ratio [RR], 0.52; 95% confidence intervals [CI], 0.40-0.67; I 2 = 26.5%), with consistent results observed in RCTs (3 RCTs, RR, 0.26; 95% CI, 0.09-0.77; I 2 = 44.4%) and observational studies (4 studies, RR, 0.54; 95% CI, 0.41-0.72; I 2 = 44.4%). Based on results from 6 studies, serum creatinine concentration was lower following treatment with imipenem-cilastatin than comparators (weighted mean difference in serum creatinine -0.14 mg/dL (95% CI, -0.21 to -0.07; I 2 = 0%). The overall certainty of the evidence was low due to heterogeneity of the results, high risk of bias, and indirectness among the identified studies.

Limitations

Clinical and statistical heterogeneity could not be fully explained due to a limited number of studies.

Conclusions

Patients treated with imipenem-cilastatin developed AKI less frequently and had lower serum creatinine concentration following treatment than control groups or those who had received comparator antibiotics. Larger clinical trials with less risk of detection bias due to lack of allocation concealment and blinding are needed to establish the efficacy of cilastatin for AKI prevention.

Predictors of Skeletal Muscle Index for Patients Treated With Hemodialysis

OBJECTIVE

There is an increased risk of skeletal muscle mass (SMM) loss among patients with stage 5 chronic kidney disease treated with maintenance hemodialysis (MHD). The reduced SMM considerably influences the development of protein-energy wasting (PEW). Patients who develop PEW have higher hospitalization and mortality rates than those without PEW. This study determined if key variables could predict SMM Index (SMM adjusted for height) in patients receiving MHD.

METHODS

We conducted a secondary analysis of cross-sectional data obtained from the Rutgers Nutrition and Kidney Database (n = 178). Data were used to calculate both SMM and SMM Index. Univariate and multiple linear regression models explored the relationship between SMM Index and the following variables: serum albumin, urea clearance normalized treatment ratio, normalized protein catabolic rate, serum creatinine, and urea reduction ratio (URR).

RESULTS

Most participants were Black/African American (82.9%), male (59.1%), and obese (39%), with a mean age of 55.9 ± 11.9 years. The median Subjective Global Assessment score was 5, indicating a lower risk of malnutrition. Participants had a mean SMM of 26.4 kg and a median SMM Index of 8.9 kg/m2. Univariate regression modeling found URR to be a significant predictor of SMM Index, with increases in the percentage of URR predicting lower SMM Index values. The adjusted regression modeling found similar results, with increases in URR percentage predicting declines in SMM Index.

CONCLUSION

This study found that URR was a predictor of SMM Index in patients receiving MHD. Further research is required to explore these relationships and provide clinicians with a more extensive array of tools to recognize early signs of SMM loss to prevent the progression of PEW.

Lean body mass in living kidney donors impacts postoperative renal function

PURPOSE

A living donor kidney transplant is the optimal treatment for chronic renal impairment. Our objective is to assess if lean skeletal muscle mass and donor factors such as body mass index, hypertension, and age impact on renal function following donor nephrectomy.

METHODS

Potential donors undergo CT angiography as part of their work-up in our institution. Using dedicated software (Horos®), standardized skeletal muscle area measured at the L3 vertebrae was calculated. When corrected for height, skeletal muscle index can be derived. Skeletal muscle mass index below predefined levels was classified as sarcopenic. The correlation of CT-derived skeletal muscle index and postoperative renal function at 12 months was assessed. Co-variables including donor gender, age, body mass index (BMI), and presence of pre-op hypertension were also assessed for their impact on postoperative renal function.

RESULTS

275 patients who underwent living donor nephrectomy over 10 years were included. Baseline pre-donation glomerular filtration rate (GFR) and renal function at one year post-op were similar between genders. 29% (n = 82) of patients met the criteria for CT-derived sarcopenia. Sarcopenic patients were more likely to have a higher GFR at one year post-op (69.3 vs 63.9 mL/min/1.73 m2, p < 0.001). The main factors impacting better renal function at one year were the presence of sarcopenia and younger age at donation.

CONCLUSION

When selecting donors, this study highlights that patients with low skeletal mass are unlikely to underperform in terms of recovery of their renal function postoperatively at one year when compared to patients with normal muscle mass and should not be a barrier to kidney donation.

The long-lasting effect of early life family structure on social position, well-being, and biological condition in adulthood

BACKGROUND

The absence of even one parent has short- and long-term effects on the child's current and future health. The purpose of the study was to determine whether there is a long-term relationship between the type of family in which men were raised and an individual's adult social position, well-being in adulthood and their biological condition regardless of social status in adulthood.

MATERIALS AND METHODS

Data for 4528 males, aged 25-80 years, were selected from the archives of the Lower Silesian Medical Centre in Wrocław, Poland. A total of 329 men declared that they grew up in incomplete families. Height, weight, % fat, cardiovascular and respiratory systems, blood parameters, and health of men who grew up in complete or incomplete families were compared.

RESULTS

Growing up in an incomplete family reduced chances for better education, decreased life satisfaction in adulthood, and negatively affected the final height. After taking into account the education achieved, the effect persisted only for diastolic blood pressure, creatinine, and serum phosphorus levels.

CONCLUSIONS

Growing up in an incomplete family has a significant impact on male's socioeconomic position (SES), life satisfaction, and final height. A poorer quality of diet is proposed as an early life risk factor for adult health.