The following is a summary of “Assessment of epidemiology and outcomes of adult patients with kidney-limited thrombotic microangiopathies,” published in the May 2024 issue of Nephrology by Maisons et al.

Thrombotic microangiopathies (TMA) are often linked with blood-related issues (RH-TMA), but the understanding of kidney-limited TMA (RL-TMA) is unclear.

Researchers conducted a retrospective study to identify and analyze cases of RL-TMA in patients who underwent kidney biopsies better to understand the epidemiology and outcomes of kidney-focused TMA.

They identified patients with TMA who had native kidney biopsies at 20 French hospitals between 2009 and 2022. The results from these biopsies were analyzed to assess the prevalence, causes, and outcomes of RL-TMA compared to RH-TMA.

The results showed that out of 757 patients with TMA, 45% (341 patients) had RL-TMA, which was associated with lower levels of creatinine compared to RH-TMA (median 184 vs. 346 µmol/L). RL-TMA had diverse causes, with frequent associations seen with anti-VEGF treatment and hematological cancers but less with specific triggers like shigatoxin-associated hemolytic uremic syndrome (HUS), systemic sclerosis, gemcitabine and bacterial infection or with multiple triggers combined (RL-TMA: 5%; RH-TMA: 12%). RL-TMA showed lower rates of major cardiovascular events (10% vs. 20%), kidney replacement therapy (23% vs 43%), and death (12% vs 20%) than RH-TMA during a median follow-up of 28 months compared to RH-TMA. Atypical HUS (aHUS) was detected in 326 patients (RL-TMA: 43%, RH-TMA: 44%). Among 69 patients with confirmed complement-mediated aHUS, 62% received eculizumab (RL-TMA: 35%, RH-TMA: 71%). Eculizumab was used in 29 out of 257 patients with aHUS, including 51% with RL-TMA, with uncertain treatment effects.

Investigators concluded that RL-TMA is a significant part of TMA cases with diverse causes. While outcomes are better than RH-TMA, there are still notable adverse events. Notably, eculizumab use in RL-TMA needs further study.

Source: kidney-international.org/article/S0085-2538(24)00170-4/abstract#%20