Topic Discussion: COVID-19 and the Kidney

Coronavirus disease 2019 (COVID-19) causes a severe acute respiratory syndrome. Similar to SARS outbreak, this virus has caused the 2019-2020 outbreak. It presents with a dry cough, fever, running nose, fatigue and shortness of breath. The elderly, hx of pulmonary disease, immunocompromised are at risk. Mortality rate is around 2-3% from ongoing outbreaks. 

How does this virus affect the Kidney. First and foremost, what is the data on transmission via dialysis units and infection in dialysis patients. Wuhan, China was where the outbreak occurred and started. In a single center study under open access review, 37 cases ( 16%) of HD patients were infected. 7 HD patients died and 6 had COVID-19 during this epidemic. The precaution measures taken by HD units prevented further cases. For some unclear reason, while HD patients were more likely to get this infection, the cases were milder than non HD counterparts. 

Here is the ASN suggestions for HD units for COVID-19 screening and precautions.

What about AKI? Is it common?  Again from Wuhan, in the month of the major outbreak in China, < 20 patients showed mild elevations in BUN and crt and trace albuminuria. 5 patients required CRRT. 
All patients that had CKD after this survived. Moreover, SARS-CoV-2 RNA in urine sediments was positive only in 3 patients from 48 cases without renal illness before, and one patient had a positive for SARS-CoV-2  from 5 cases with CKD. Interpretation Acute renal impairment was uncommon in COVID-19. SARS-CoV-2 infection does not significantly cause obvious acute renal injury, or aggravate CKD in the COVID-19 patients.

Interestingly, another center reported a different finding.  A large tertiary center in China studied 710 consecutive COVID19 patients, 89 (12.3%) of whom died in hospital. On admission, 44% of patients have proteinuria hematuria and 26.9% have hematuria, and the prevalence of elevated serum creatinine and blood urea nitrogen were 15.5% and 14.1% respectively. During the study period, AKI occurred in 3.2% patients. Kaplan-Meier analysis demonstrated that patients with kidney impairment have higher risk for in-hospital death. Cox proportional hazard regression confirmed that elevated serum creatinine, elevated urea nitrogen, AKI, proteinuria and hematuria was an independent risk factor for in-hospital death after adjusting for age, sex, disease severity, leukocyte count and lymphocyte count. Conclusion: The prevalence of kidney impairment (hematuria, proteinuria and kidney dysfunction) in hospitalized COVID-19 patients was high. After adjustment for confounders, kidney impairment indicators were associated with higher risk of in-hospital death. This was in strike contrast to the prior study.

Finally, hypokalemia was a common electrolyte finding in these patients. One would think GI cause as the cause, but GI symptoms were not associated with hypokalemia among 108 hypokalemia patients. Body temperature, CK, CK-MB, LDH, and CRP were significantly associated with the severity of hypokalemia. 93% of severe and critically ill patients had hypokalemia which was most common among elevated CK, CK-MB, LDH, and CRP. Urine K+ loss was the primary cause of hypokalemia.