Introduction:
Thrombotic Microangiopathy (TMA), as the name implies, involves pathologic lesion due to abnormality in the vessel wall of arterioles and capillaries leading to microvascular thrombosis. Clinically presents as microangiopathic haemolytic anaemia, thrombocytopenia and organ injury, AKI being a common and prominent feature. It is a pathologic diagnosis made by biopsy. There are multiple aetiologies of TMA _ immune mediated, complement mediated, Shiga toxin induced, hereditary, secondary causes like post-transplant, drug induced, malignancy related and other systemic diseases. 2 major clinically different entities have been described _ HUS (Hemolytic uremic syndrome) and TTP (Thrombotic thrombocytopenic purpura). TTP was first described in 1924 by Moschowitz. Term HUS was introduced in 1955 by Gasser and Co-workers.
HUS occurs more commonly in children with an incidence of 5-6/million children per year, 90% of which is associated with diarrheal diseases due to Shiga-like toxin producing E coli (STEC). Atypical HUS (aHUS) is less common with an incidence of 0.5 - 2/million per year, majority of which would progress to ESRD (End stage renal disease) or death due to non-availability of complement inhibition therapy. Incidence of TTP is 2-4/million per year. TMA in post-transplant recipients can be a manifestation of recurrence of primary aetiology, de novo TMA, drug induced, infection related or part of antibody mediated rejection process. The pathologic findings reflect tissue response to endothelial injury including endothelial swelling and mesangiolysis in active lesion and double contour of the basement membrane in chronic lesions.
A systematic approach to investigate and prompt initiation of supportive management, effective specific treatment in few cases, can result in good outcomes. We reviewed the spectrum of TMA presenting to the department of Nephrology at our centre in the last 5 years and studied the clinical profile of these patients.
Methods:
Renal biopsies of patients between January 2019 to December 2023 (last 5 years) were retrospectively reviewed and patients with biopsy proven TMA were included. Their electronic data were reviewed to understand the aetiology, clinical profile and prognosis. Patients presenting to the Critical Care Unit with Sepsis related TTP were excluded.
Results:
n = 6
Primary TMA = 1 (recurrence of aHUS post transplant)
Secondary TMA = 5 (drug induced 1, Connective tissue disease 2, Malignant Hypertension induced 1, Cobalamin C deficiency related 1)
Need for Dialysis = 2
Complete recovery = 4
Chronic kidney disease = 1
End stage renal disease = 1
Post Transplant = 2 (drug induced 1, recurrence of aHUS 1)
Clinical Presentation _ Constitutional symptoms, Haemolysis, Thrombocytopenia, Acute Kidney Injury in 5/6. Gastrointestinal bleed in 1/6.
Conclusions:
The incidence of Shiga toxin induced HUS has been zero in our review and so was the occurrence of aHUS, there was recurrence of aHUS post-transplant in 1 patient. We had a majority of secondary TMA with good prognosis once the aetiology was identified early and treated. ADAMTS 13 was negative in all 6 of them suggesting a very rare incidence of hereditary causes of TMA. Contrary to the literature, incidence of primary causes in TMA were far lesser in our analysis compared to secondary causes.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.