The diagnosis of COVID-19 can be challenging as patients often present with unclear or even subclinical signs of disease. [8]
In our study, none of the COVID-19 patients reported any LUTS or had urinary retention or incontinence. Even in those 12 patients who tested positive for viral RNA in their urine. A study that focused on an increase in urinary frequency as a symptom of COVID-19 identified this in seven males out of 57 patient admitted with COVID-19 [5]. Interestingly, no viral RNA was found in the urine of these patients[5]
In our series the two cohorts of Tabriz and Aachen, were not statistically different regarding age and male-female ratio (p-value 0,18 and 0,28).
The mortality rate in Tabriz (48%) was significantly higher than in Aachen 30% (p-value 0.001). This might be explained by the availability of resources as well as patient comorbidities which was not investigated in our study. There were significantly less patients who had a urine culture in the Tabriz cohort which would explain the differences in the positive culture rates.
Microscopic haematuria was seen in a majority of tested COVID-19 patients of Tabriz and Aachen (68% and 78%, respectively) and was not due to a positive bacterial urine culture in most cases (Table 1).
Hematuria has been reported in other viral respiratory infections including influenza A and B as well as adenovirus [9]. Moreover, kidney injury in hospitalized patients with COVID-19 appears to be a frequent finding. [10] Different symptoms have been reported ranging from, from mild hematuria to severe renal failure[9]. The underlaying pathophysiology is not well known. However, hypotheses have been put forward on the cytopathic effects of the virus as well as the immune-complexes mediated damage[9]. Furthermore, indirect effects on renal tissue, including hypoxia, and rhabdomyolysis due to the cytokine inflammatory response to the virus might play a role as well.
In our study, we have found increase white blood cells (WBC) in the urine of about half of the tested COVID-19 patients (Table 2). In most of the cases there was a negative bacterial urine culture.
The time from suspected exposure to the onset of COVID-19 and worsening hematuria ranged between 5 and 8 days in the reported cases.
In the face of a possible increase and new waves of the pandemic, clinicians should be aware that a non-typical course of hematuria or increased WBC in urine might be related to a COVID-19 infection, especially in patients with a preexisting condition of the urinary tract.[10]
It is known that the mortality rates are high between the COVID-19 patients with acute kidney injury (60-90%)[11].
Viral RNA has been identified in the urine samples of COVID-19 patients even after recovery from respiratory symptoms[6]. In our study, SARS-CoV-2 was found in the urine of 19 % of the tested patients.
Angiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2 and responsible for host cell entry might be a another possible link to multi organ failure of the COVID-19 patients. ACE2 is expressed different organs such as the hearth, the gastrointestinal tract, bone marrow and kidneys and bladder.[12]
Recent studies revealed the cell-surface protein angiotensin-converting enzyme 2 (ACE2) as the main receptor for the SARS-CoV-2 spike protein[13]. Investigations of the distribution across many different tissues revealed that ACE2 expression was highest in lung, intestines, and kidney, but it was also high in 2.4% of urothelial cells, which might be a link with lower urinary tract symptoms[14] . In Next to the kidney tissue bladder urothelium has cells that express ACE2 [10, 14, 15] We hypothesize a possible link between the lower urinary system and SARS-CoV-2 through the ACE2. (Figure 1)
Regarding the urine analysis of COVID-19 patients in our study, we can state that the presence of WBC and RBC in the urine as well as the presence of COVID-19 virus in urine, seems directly related to an increase of mortality in these patients (table 2). In patients with microscopic hematuria together with white blood cells in their urine, the mortality was significantly increased from 48% to 61% in the Tabriz cohort (p-value=0.03) and from 30 % to 35% in the Aachen cohort (p-value =0.045). In addition, Moreover, in the group of patients with SARS-CoV-2 urine PCR, the mortality rate rose from 33% to 50%. (p-value =0.039).