Post exertional hematuria

Abstract

The incidence of exercise-induced hematuria is reported to be between 5% and 25% and available literature suggests that it lasts for a few hours to a maximum of 3 days. We analyzed the urine sediment of healthy participants between the age of 20 and 50 years before and after a 5 km run. Anyone with abnormal pre-exercise sediment was excluded from the study. Of 491 participants, 59 (12%) developed post exercise hematuria when the run had to be completed in allotted time. However, when the run was completed without time limit, only 1.3% (4 of 316) developed hematuria (p < 0.001). We found that the younger participants (age < 30 years) had a significantly higher incidence of hematuria as compared to their older compatriots (p = 0.019). The mean duration of hematuria was 1.98 ± 1.89 days and 81% of the participants cleared their hematuria within 3 days. In 12% it lasted between 3 and 7 days and in 7% it continued beyond 7 days. Three individuals had persistence of hematuria beyond day 14 and all these were found to have primary glomerular disease on renal biopsy [two had IgA nephropathy and one focal segmental glomerulosclerosis (FSGS)]. We conclude that exercise-induced hematuria can last up to a fortnight. However, if it persists beyond a fortnight, it is unlikely to be functional and an underlying cause is likely. Hematuria following exercise seems to be related to the intensity of effort during exercise rather than its duration.

• Exercise
• hematuria

Introduction

The incidence of post exercise hematuria varies from 5% as reported in Israeli Air Force recruits1 to over 20% in trained athletes.2–4 In 1910, Barach5 reported proteinuria, granular casts and hematuria in marathon runners, which was later labeled as “athletic pseudonephritis”.6 Thereafter, many investigators have tried to localize the source of this transient exertional hematuria and proteinuria. Blacklock7 attributed it to bladder trauma during exercise. Fassett et al. based on presence of dysmorphic RBC suggested its origin to the glomerulus,8 while others have suggested foot strike induced trauma and resultant hemolysis as the underlying pathology.9–11 Some workers have suggested acidosis and hypoxia-related glomerular injury as the cause12–15; however, recent data suggest it to be originating from lower tract.12–15

McInnis et al.16 observed that post exertional hematuria is greater after intense weight bearing exercise rather than long duration non weight bearing exercise like cycling. Falsetti et al.,9 Poortmans and Jeanloz13 and Helzer et al.17 observed that the intensity of exercise correlated with urinary abnormalities. Jones et al.18,19 observed a greater amount of hematuria following higher intensity of exercise done over a shorter duration of time. They found higher incidence of hematuria with runs over short distances (600–1500 m), while the same athletes produced fewer RBCs despite running longer distances but over longer periods of time.

The hematuria induced by exercise lasts for a maximum of 72 h, and subsides spontaneously.2–4 However, Sun Young Na et al.20 reported a case in which hematuria persisted for 7 days.

Materials and methods

Fit and healthy males (without any co morbidity) between the ages of 20 and 50 years who volunteered to participate in the study were the subjects. In phase I, all of them ran a distance of 5 km at 0630 h. Each one of them had urine routine and microscopic examination before and after the exercise. The time schedule (in minutes) for successful completion of the run varied with age; 25 min for those under 30 years, 26.5 m for those between 30 and 40 years and 28 m for participants over the age of 40 years. In phase II of the study these participants ran for the same distance after a gap of one month. This time there was no time limit for completion of run.

All were required to provide 15 mL of pre-exercise mid stream urine 15 min prior to the run. Similar amount of post exercise urine was also collected in a sterile container. Both the samples were immediately transferred to laboratory in ice and kept at 2–8 °C till testing. There was no restriction of fluids prior to the start of the run, and the participants were not made to empty their bladder. They had no access to fluids during the duration of the run.

All the samples were tested within 2 h of collection by Siemens automated urine analyser using 10 parameter reagent strip and special emphasis was given to RBC and protein testing. Quality control was confirmed using QC strips from Siemens™. The samples which showed positive test for hematuria were centrifuged at 2000 rpm for 2 min and the sediment was analyzed for RBCs under light microscope. A participant was said to have hematuria if there were more than 3 RBCs /HPF under 400x magnification on light microscopy. Other features included in microscopy were presence of neutrophils, RBC casts or other casts, crystals and epithelial cells. However in this study we have only commented on hematuria.

The participants who tested positive for hematuria were required to submit their urine samples daily to the hospital lab for hematuria test till it cleared. The time period required for disappearance of hematuria was noted. Individuals who continued to have hematuria beyond 14 days post exercise were admitted. Their evaluation included, hematological and biochemical investigations along with a detailed renal imaging with ultrasound scan, non-contrast computed tomography of kidneys, ureters and bladder (NCCT KUB) followed by a renal biopsy. The biopsy specimen was subjected to light microscopy using hematoxylin and eosin, Periodic Acid Schiff, Periodic Acid Silver Methenamine and MT stain. Immunofluorescence studies were done after cryostat sections were stained with fluorescein isothiocyanate (FITC) tagged anti IgG, IgM, IgA, C3, fibrin, C1q, kappa, lambda and albumin. A part of the kidney biopsy was preserved in glutaraldehyde for electron microscopy in case the light microscopy and IF studies did not reveal any abnormality.

Observations

In phase I, 491 males took part in this study. The age wise distribution of incidence of hematuria is as given in Table 1.

Table 1. Age distribution and incidence of hematuria.

S No	Age group (years)	Number (%)	Hematuria (%)
1	20–30	251 (51)	39 (15.5)
2	31–40	91 (18)	07 (7.7)
3	41–45	97 (20)	09 (9.2)
4	46–50	52 (11)	04 (7.7)
	Total	491	59 (12)

Of these 491 individuals, 59 (12%) were found to have post exercise hematuria. The incidence of hematuria was greatest in the younger age group (<30 years): 39 of 251 (15.5%) young participants had hematuria, a significantly higher incidence compared to their older comrades (>30 years, 20 of 240) (8.4%) (p = 0.019). Younger participants had lesser time to complete the run and hence exerted harder, which explains higher incidence of hematuria in them. Hematuria lasted for a mean duration of 1.98 ± 1.89 days (±1 SD). The distribution is given as in Table 2. There was no significant difference in the duration of hematuria in the various age groups. Only three participants had hematuria lasting over 14 days. These individuals on evaluation (including renal biopsy) were found to have primary glomerular disease – one had focal segmental glomerulosclerosis (FSGS) and two had IgA nephropathy.

Table 2. Distribution of duration of hematuria.

Duration in days	1–3	4–7	>7
No. (%age)	48 (81)	7 (12)	4 (7)

In phase II of the study, 316 participants ran the same distance after a month. However, this time there was no time limit to complete the distance. Only four participants (1.3%) developed hematuria. The hematuria lasted for 1, 2, 4 and 4 day respectively in them.

Discussion

We observed that exercise-induced hematuria is a frequent finding in young adults. The incidence of 12% hematuria after the run seen in our study is more in tandem with that found in Israeli Air Force recruits (5%),1 unlike the incidence of >70% seen in hard core athletes like ultra marathoners,3 long distance skiers or 45% in professional athletes.9–14 All investigators have commented that post exertional hematuria subsides within 72 h.2–4,12,16,18 However, 19% of our subjects had persistence of hematuria beyond 72 h, and three individuals continued to have hematuria beyond 14 days. On evaluation, they were found to have primary glomerular disease. It is possible that these individuals had disease beneath the clinical horizon of detection and the physical stress of the 5 km run unmasked the disease and led to persistent hematuria beyond 14 days. We did not perform electron microscopic evaluation of the biopsies of these individuals as the diagnosis was confirmed on light microscopy with IF studies.

We also found that there was a significantly higher incidence of hematuria in the young runners (<30 years) when compared to their older compatriots. The young runners had to exert harder than their older compatriots as they had lesser time to complete the run, this explains the significantly higher incidence of hematuria in them. The second phase of the study proved this point when the incidence of hematuria dropped drastically with removal of the time limit to complete the run. This correlates with the findings of Falsetti et al.,9 Poortmans and Jeanloz,13 Helzer et al.17 and Jones and Newhouse,18 who found that the incidence of hematuria increases with the intensity of exercise rather than its duration.

The source of hematuria in our patients could not be commented upon with confidence, as we did not perform phase contrast microscopy on the urine samples. Most workers consider the origin of the RBCs to be from the lower urinary tract. An electron microscopic analysis of the biopsy tissue could have isolated cases of thin membrane disease. However as glomerular lesions were detected on light microscopy of the biopsy, we are tempted to opine that the origin of hematuria could be glomerular too.

The strengths of our study are:

1. The large number of individuals who participated in the designed run.

2. Demonstration that hematuria can last longer than the usual reported period of 3 days and occasionally even up to 14 days.

3. Younger participants who had lesser time for run had higher degree of hematuria.

4. Proof that exercise can probably unmask underlying glomerular disease.

Conclusions

Exercise-induced hematuria after a 5 km run is a frequent finding and was observed in 12% of participants. It appears to be associated with the intensity of exercise rather than its duration. It can last up to a fortnight, however if it lasts longer one should look for underlying renal disease.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.