Renal Involvement in Upshaw-Schulman Syndrome

What Is Upshaw-Schulman Syndrome?

Upshaw-Schulman syndrome is a less-known and infrequent variant of thrombotic thrombocytopenic purpura that develops by birth or is inherent in nature, also called congenital thrombotic thrombocytopenic purpura. Thrombotic thrombocytopenic purpura, otherwise known as TTP, is an ailment inflicted by thrombocytopenia (depleted platelet count) and hemolytic anemia (collapse in hemoglobin or red cell proportion prompted by premature destruction and disintegration of red blood cells).

Thrombotic thrombocytopenic purpura can be brought out either by birth (congenital) or develop later in life (acquired). A deficit or downfall in ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13), which is a protease (an enzyme that could fragment and process proteins) that could cleave the clotting factor, von Willebrand factor, cutting down its size.

As a result of the ADAMTS13 deficiency, the von Willebrand factor’s dimension builds up, giving rise to ULVWF (unusually large Von Willebrand factor) multimers, which in turn favors and augments the emergence of tiny blood clots within the blood vessel, so-called microthrombi, by the gathering and clumping of von Willebrand factor and platelet cells. These microthrombi could hamper and occlude several tiny blood vessels, hindering the supply to vital structures like a kidney. Upshaw-Schulman syndrome, being an inborn variant of TTP, is instigated by an aberration in the ADAMTS13 gene, which governs and encodes for the ADAMTS13 enzyme.

What Are the Clinical Manifestations of Upshaw-Schulman Syndrome?

The key manifestations brought out by Upshaw-Schulman syndrome include:

• Microangiopathic Hemolytic Anemia: A collapse in red cell count prompted by premature red cell mutilation. The microthrombi choke and occlude the blood vessel, and at times, it leaves a tiny passage for the blood to move in. As the red cells squeeze through these tiny passages, many of the functionally active red cells will get fragmented and mutilated, giving rise to hemolytic anemia. As hemolytic anemia is inflicted by the diminution of the blood vessel lumen, it is often denominated as microangiopathic hemolytic anemia (MAHA).

• Thrombocytopenia: As more microthrombus evolve, more of the platelets in the blood will be consumed and used up in the process, which reflects an appreciable downfall in the platelet count, prompting thrombocytopenia. Greater propensity for bleeding, nose bleeds, heavy menstrual bleeding, bloody urine, and stool are the manifestations that signal thrombocytopenia.

• Fever: Fever is one of the pentad manifestations brought out by Upshaw-Schulman syndrome.

• Renal Dysfunction: The ADAMTS13 deficit also instigates functional disparities in the kidneys, bringing about several kidney issues, like hematuria (blood-tinged urine).

• Neurological Dysfunction: Neurological functions are also deranged or downturned with Upshaw-Schulman syndrome.

What Is the Renal Involvement in Upshaw-Schulman Syndrome?

Renal involvement in Upshaw-Schulman syndrome is critically significant and mandates therapeutic interventions to mitigate the derangements in kidney functions. The microthrombi that emerge from ULVWF multimers can clog and choke up the tiny renal blood vessels, inflicting microangiopathy. Microangiopathic renal blood vessels could eventually contribute to microangiopathic hemolytic anemia and subsequent thrombocytopenia.

As the microthrombi choke up the renal blood vessels, an adequate proportion of blood cannot move and flows into all the kidney cells, inflicting blood and oxygen deficits in several vital kidney cells. Palliated blood flow to renal cells brings out hypoxia (prompted by oxygen deprivation in the renal cells), which in turn brings out functional impairment and acute kidney injury (AKI). AKI is inflicted by the abrupt malfunctioning or dysfunction of the kidneys and is an immediate-onset ailment that develops in response to microthrombi-triggered hypoxia.

The microthrombi in the glomerular capillaries (tiny capillaries that serve as the kidney’s filtering units) may invoke injury to the glomerulus. The functional aspects of the glomerulus are brought down with injury and mutilation, prompting hematuria and proteinuria. The protein molecules in the blood that are otherwise not eliminated through urine get expelled in urine through the mutilated glomerulus, thus bringing forth proteinuria. With injury, the filtering efficacy of the glomerular capillaries mitigates. Red blood cell hemolysis may leave behind certain red blood cell fragments. These fragments may ooze out and escape through the injured glomerulus and get expelled with urine, which is denominated as hematuria. In addition, hematuria could also be prompted in Upshaw-Schulman syndrome by direct bleeding of the injured glomerulus.

At times, the Upshaw-Schulman syndrome over time may inflict chronic kidney disease. The compromised renal blood flow instigated by the microthrombi gradually depletes the functional attributes of the kidneys, paving the way for chronic kidney disease. Therefore, medical management of the renal implications of Upshaw-Schulman syndrome is imperative to upkeep the functional status of the kidneys.

How Could Renal Involvement in Upshaw-Schulman Syndrome Be Managed?

To combat renal involvement in Upshaw-Schulman syndrome, strategic therapeutic plans need to be structured. Renal issues that are brought about by Upshaw-Schulman syndrome, like hematuria, proteinuria, acute kidney injury, and chronic kidney disease, are alarming and often necessitate prompt medical management. However, the cause that has prompted the renal issues, which is the Upshaw-Schulman syndrome, must be addressed primarily, and the recovery prospects are governed by how much the syndrome is balanced or mitigated. The renal issues are just the manifestations of the condition, so addressing the manifestation leaving the cause would not turn out to be a productive treatment strategy.

Since Upshaw-Schulman syndrome is genetically driven and develops by birth, attaining a complete cure is often challenging. Plasma exchange is a productive therapeutic modality for Upshaw-Schulman syndrome, where the deficit in ADAMTS13 that has prompted the manifestations is addressed by replenishing and topping up the ADAMTS13. Thus, the enzyme deficit can be palliated and could be brought back to normal. In addition to plasma exchange, plasma infusion could also be instituted to counter the ADAMTS13 deficit. Plasma loaded with the required proportion of ADAMTS13 could be employed for infusion, thus eliminating the deficit.

When renal problems are encountered alongside the conventional therapeutic modalities for Upshaw-Schulman syndrome, specific interventional strategies to mitigate the renal damage must be considered. Measures to retrieve the electrolyte and fluid balance must be employed in case they are disturbed. To mitigate the propensity for microthrombi formation, antiplatelet therapy could be instituted, provided it outweighs the prospect of bleeding; similarly, in cases where renal issues gravitate toward elevated blood pressure, that also needs to be addressed with appropriate antihypertensive medications.

Conclusion:

Though rare, Upshaw-Schulman syndrome can bring forth appreciable impairment and dysfunction in the renal system. Renal involvement in Upshaw-Schulman syndrome ought to be thoroughly monitored and tracked to mitigate the propensity for renal complications. Therefore, the kidneys and their associated structures must be safeguarded from the insidious effects of Upshaw-Schulman syndrome. Proactive measures, vigilant monitoring, and tailored therapeutic strategies enable better life quality and longevity for those with Upshaw-Schulman syndrome.