Marathon running and cell-cycle arrest biomarkers of acute kidney injury

OBJECTIVES

Endurance exercise is known to cause a rise in serum creatinine. It is not known to what extent this rise reflects renal stress and a potential acute kidney injury (AKI). Increases in Insulin Like Growth Factor Binding Protein 7 (IGFBP7) and Tissue Inhibitor of Metalloprotinases-2 (TIMP-2), urinary biomarkers of cell cycle arrest and renal stress, are associated with the development of AKI in clinical populations.

DESIGN

Repeated measures study.

METHODS

Runners were recruited at the 2019 Brighton Marathon (UK) and provided urine and blood samples at baseline, immediately post-race and 24 h post-race. Serum creatinine, urinary creatinine and urinary IGFBP7 and TIMP-2 were analysed from the samples.

RESULTS

Seventy nine participants (23 females, 56 males), aged 43 ± 10 yrs. (mean ± SD), finish time 243 ± 40mins were included for analysis. Serum creatinine increased over the race by 40 ± 26% (p < 0.001), TIMP-2 increased by 555 ± 697% (p < 0.001) and IGFBP7 increased by 1094 ± 1491% (p < 0.001) over the race. A subset of twenty-two participants supplied samples 24 h post-race, reporting values similar to baseline for all variables.

CONCLUSIONS

This study is the first to report large rises in IGFBP7 and TIMP-2 following marathon running. This suggests that rises in creatinine are not fully explained by changes in production and clearance and marathon running induces a state of kidney stress and potential injury.

Association between collapse and serum creatinine and electrolyte concentrations in marathon runners: a 9-year retrospective study

OBJECTIVE

Abnormal biochemical measurements have previously been described in runners following marathons. The incidence of plasma sodium levels outside the normal range has been reported as 31%, and the incidence of raised creatinine at 30%. This study describes the changes seen in electrolytes and creatinine in collapsed (2010-2019 events) and noncollapsed (during the 2019 event) runners during a UK marathon.

METHODS

Point-of-care sodium, potassium, urea and creatinine estimates were obtained from any collapsed runner treated by the medical team during the Brighton Marathons, as part of their clinical care, and laboratory measurements from control subjects.

RESULTS

Results from 224 collapsed runners were available. Serum creatinine was greater than the normal range in 68.9%. About 6% of sodium results were below, and 3% above the normal range, with the lowest 132 mmol/l. Seventeen percent of potassium readings were above the normal range; the maximum result was 8.4 mmol/l, but 97% were below 6.0 mmol/l. In the control group, mean creatinine was significantly raised in both the collapse and control groups, with 55.4% meeting the criteria for acute kidney injury, but had resolved to baseline after 24 h. Sodium concentration but not the potassium was significantly raised after the race compared with baseline, but only 15% were outside the normal range.

CONCLUSION

In this study, incidence of a raised creatinine was higher than previously reported. However, the significance of such a rise remains unclear with a similar rise seen in collapsed and noncollapsed runners, and resolution noted within 24 h. Abnormal sodium concentrations were observed infrequently, and severely abnormal results were not seen, potentially reflecting current advice to drink enough fluid to quench thirst.

New observations support William Osler's rationale for systemic bloodletting

Bloodletting has been called William Osler's "blind spot," especially with respect to pneumonia. Also puzzling has been his endorsement of bleeding in selected cases of heatstroke. Recent clinical observations on pneumonia and, to a lesser extent, heatstroke lend support to Osler's rationale for bloodletting in these conditions. A 21st-century rationale now exists for all eight indications for systemic bloodletting listed by Osler in the first edition of his textbook, The Principles and Practice of Medicine (1892): treatment of acute heart failure (seven of the eight indications) or rapid lowering of blood pressure (in subarachnoid hemorrhage accompanied by severe hypertension). These observations support the narrative that during Osler's lifetime, bloodletting became more "rational" largely on the basis of cumulative clinical experience.

Acute kidney injury associated with endurance events-is it a cause for concern? A systematic review

INTRODUCTION

A growing body of evidence suggests even small rises in serum creatinine (SCr) are of considerable clinical relevance. Given that participants in endurance events are exposed to potential (repeated) renal insults, a systematic review was undertaken to collate current evidence for acute kidney injury (AKI), complicating such events.

METHODS

A systematic review of studies and case reports meeting inclusion criteria on Medline and EMBASE (inception to October 2015). Included: studies with markers of renal function before and after endurance or ultraendurance events; case reports of severe AKI. Two reviewers assessed risk of bias using the Newcastle-Ottawa scale.

RESULTS

Eleven case report publications (n=27 individuals) of severe AKI, were retrieved, with risk factors including systemic illness or nephrotoxic medications usually identified. From 30 studies of endurance and ultraendurance events, mean rise in SCr was 29 (±12.3) µmol/L after marathon or ultramarathon (17 studies, n=568 participants) events. Where follow-up tests were conducted, SCr returned to baseline within 48 hours. Rises in biomarkers suggest potential parenchymal insult, rather than simply muscle breakdown. However, evidence of long-term deleterious effects is lacking.

CONCLUSIONS

Raised levels of SCr are reported immediately after endurance events. It is not clear whether this is either clinically significant, or if repeated participation predisposes to long-term sequelae. The aetiology of severe exercise-associated AKI is usually multifactorial, with risk factors generally identified in the rare cases reported. On-site biochemistry, urine analysis and biomarkers of AKI may help identify collapsed runners who are at significant short-term risk and allow suitable follow-up.