Atypical Hemolytic Uremic (Ahus) Syndrome With Kidney Injury In Pediatric Patient : A Case Report

Hemolytic uremic syndrome is a form of thrombotic microangiopathy (TMA) which is characterized by thrombocytopenia, microangiopathy hemolytic anemia and renal impairment.1

HUS is classified as typical hemolytic uremic syndrome and atypical hemolytic uremic syndrome (aHUS). Typical hemolytic uremic syndrome also called as STEC-HUS (for Shiga toxin–producing Escherichia coli HUS) Caused by Shiga toxin, E.coli, or shigella. aHUS caused by dysregulation of alternative pathway.5

Approximately 10% of cases of the hemolytic–uremic syndrome is classified as atypical, since they are not caused by either Stx-producing bacteria or streptococci. 3

Vascular endothelial cell injury is the key mechanism underlying all forms of HUS, these can be caused by inflammatory and non-inflammatory mechanism.2

The clinical presentation of aHUS in children and adults are often nonspecific including pallor, poor feeding, vomiting, fatigue, and drowsiness. Renal involvement may manifest as oliguria or anuria with or without peripheral edema. HTN is also an important manifestation that develop due to renal injury which can cause neurological complication or cardiac failure. 4

Early recognition and initiation of appropriate treatment are essential in patient with a HUS which involves supportive care and inhibition of complement system. Plasmatherapy is recommended as first line treatment approach for aHUS. It should be started within 24 hours of diagnosis with 20-30ml/kg body weight.3,7

Persistent hemolysis and or failure of platelet count improvement within 4-5 days after plasmatherpay is indication of failure of treatment hence should be stopped immediately, and start eculizumab it.4

Appropriate fluid and electrolyte management is a key component of HUS treatment. Dehydrated patients should be given appropriate fluid replacement, however excessive fluid overload should be avoided especially with patients developing oliguria. Hyponatremia occurs in renal injury hence it corrected carefully by hypertonic saline. Other electrolyte abnormalities (hyperkalemia, hypophosphatemia) in initially managed medically, if severity persist dialysis and hemofiltration may be required. HUS patient with high catabolic rate is managed by giving carbohydrate’s and amino acid. If hemoglobin reduces below 6g/dl prbc transfusion is recommended. 2

Some patients with delayed diagnosis or irresponsive to therapy progress to ESRD. Renal replacement is done is such cases. Posttransplant HUS occurs in four clinical contexts that are inherited HUS, idiopathic HUS, de novo occurrence of HUS after renal transplant. Eculizumab is also used prophylactically to prevent reoccurrence of HUS after renal transplantation.2,4,

Case report:

A 7 yrs old male patient admitted in pediatric medicine department Karnataka Medical College and Research Institute (KMCRI) Hubballi, on 22 april 2026

Chief complaints:

This patient was referred from his native  government hospital i/v/o vomiting, fever, headache, periorbital puffiness since 4 days, With h/o hematuria

Physical examination:

Pallor - +ve, Icterus - +ve, clubbing - -ve, cyanosis - -ve, lympedenopathy - -ve, edema - -ve.

Vital parameters:

Table : 1 Vital parameters:

Anthropometry:

Anthropometry assessment revealed weight, height, BMI and other parameters were appropriate for age, gender with no evidence of malnutrition

Table : 2 Systemic examination:

Table : 3 Neurological examination:

Table : 4 Hematological report:

Peripheral smear report:

RBC- microcytic hypochromic with macroovulocytes with few nucleated RBC’s and good number of acanthocytes.

Impression:

Microcytic hypochromic anemia with relative lymphocytosis and thrombocytopenia.

Table : 5 LFT:

Table : 6 Arterial blood gas analysis:

Urine routine analysis:

Table : 7 Chemical examination:

Table : 8 Microscopic examination:

Urine culture and sensitivity test: no growth

Stool culture and sensitivity test: no enteric bacterial pathogen isolated

Ultrasonography reports:

-mild hepatosplenomegaly with increased echotexture of liver

-b/l kidney- bulky with increased echotexture and loss of CMD- likely s/o renal parenchymal diseases with RI values less than 0.8

-wedge shaped hypodensity seen in upper poles of right kidney? infract

-minimal interbowel loop fluid.

The patient was diagnosed with atypical hemolytic uremic(aHUS) syndrome. The patient underwent a detailed clinical examination including assessment of vital signs, systemic examination, physical examination, neurological examination, peripheral blood smear, hematological investigations, routine urinalysis, ASLO test, USG of abdomen, urine and stool culture and sensitivity test. The vital signs and anthropometry were normal, on physical examination pallor and icterus was seen. In systemic examination the tenderness was present in right upper quadrant, neurological examination showed mild weakness with normal reflexes. The low hemoglobin level with marked LDH and peripheral blood smear raised suspicion of hemolytic anemia. Whereas elevated urea, creatinine, abnormal LFT and USG report demonstrated significant renal involvement, the arterial blood gas investigation showed metabolic acidosis these findings were considered supportive of the patient systemic and renal dysfunction. In view of the combination of anemia, thrombocytopenia, biochemical evidence of hemolysis (elevated LDH, indirect bilirubin, reticulocyte count) and renal dysfunction, a thrombotic microangiopathy was suspected. HUS was considered as differential diagnosis. Urine and stool culture sensitivity and ASLO test were negative for an infectious etiology making typical HUS less likely. The clinical presentation, laboratory evidence of TMA and predominant renal involvement subsequently supported the diagnosis of atypical hemolytic uremic syndrome after exclusion of other causes of TMA. For treatment four sessions of dialysis were performed to manage AKI and patient developed severe HTN after first dialysis hence he was treated with tablet nefidipine and later titrated and shifted to tablet amlodipine when BP subsequently shows decreasing trends. plasmapheresis was done to which patient responded well hence continued the same treatment. Other medications such as paracetamol, emeset, calcium, multivitamins, were given as supportive therapy.

Table : 9 Treatment chart:

Hemolytic uremic syndrome is a form of thrombotic microangiopathy (TMA) which is characterized by thrombocytopenia, microangiopathy hemolytic anemia and renal impairment.1

HUS is classified as typical hemolytic uremic syndrome and atypical hemolytic uremic syndrome (aHUS). Typical hemolytic uremic syndrome also called as STEC-HUS (for Shiga toxin–producing Escherichia coli HUS) Caused by Shiga toxin, E.coli, or shigella. aHUS caused by dysregulation of alternative pathway.5

Approximately 10% of cases of the hemolytic–uremic syndrome is classified as atypical, since they are not caused by either Stx-producing bacteria or streptococci. 3

Vascular endothelial cell injury is the key mechanism underlying all forms of HUS, these can be caused by inflammatory and non-inflammatory mechanism.2

The clinical presentation of aHUS in children and adults are often nonspecific including pallor, poor feeding, vomiting, fatigue, and drowsiness. Renal involvement may manifest as oliguria or anuria with or without peripheral edema. HTN is also an important manifestation that develop due to renal injury which can cause neurological complication or cardiac failure. 4

Early recognition and initiation of appropriate treatment are essential in patient with a HUS which involves supportive care and inhibition of complement system. Plasmatherapy is recommended as first line treatment approach for aHUS. It should be started within 24 hours of diagnosis with 20-30ml/kg body weight.3,7

Persistent hemolysis and or failure of platelet count improvement within 4-5 days after plasmatherpay is indication of failure of treatment hence should be stopped immediately, and start eculizumab it.4

Appropriate fluid and electrolyte management is a key component of HUS treatment. Dehydrated patients should be given appropriate fluid replacement, however excessive fluid overload should be avoided especially with patients developing oliguria. Hyponatremia occurs in renal injury hence it corrected carefully by hypertonic saline. Other electrolyte abnormalities (hyperkalemia, hypophosphatemia) in initially managed medically, if severity persist dialysis and hemofiltration may be required. HUS patient with high catabolic rate is managed by giving carbohydrate’s and amino acid. If hemoglobin reduces below 6g/dl prbc transfusion is recommended. 2

Some patients with delayed diagnosis or irresponsive to therapy progress to ESRD. Renal replacement is done is such cases. Posttransplant HUS occurs in four clinical contexts that are inherited HUS, idiopathic HUS, de novo occurrence of HUS after renal transplant. Eculizumab is also used prophylactically to prevent reoccurrence of HUS after renal transplantation.2,4,

Case report:

A 7 yrs old male patient admitted in pediatric medicine department Karnataka Medical College and Research Institute (KMCRI) Hubballi, on 22 april 2026

Chief complaints:

This patient was referred from his native  government hospital i/v/o vomiting, fever, headache, periorbital puffiness since 4 days, With h/o hematuria

Physical examination:

Pallor - +ve, Icterus - +ve, clubbing - -ve, cyanosis - -ve, lympedenopathy - -ve, edema - -ve.

Vital parameters:

Table : 1 Vital parameters:

Anthropometry:

Anthropometry assessment revealed weight, height, BMI and other parameters were appropriate for age, gender with no evidence of malnutrition

Table : 2 Systemic examination:

Table : 3 Neurological examination:

Table : 4 Hematological report:

Peripheral smear report:

RBC- microcytic hypochromic with macroovulocytes with few nucleated RBC’s and good number of acanthocytes.

Impression:

Microcytic hypochromic anemia with relative lymphocytosis and thrombocytopenia.

Table : 5 LFT:

Table : 6 Arterial blood gas analysis:

Urine routine analysis:

Table : 7 Chemical examination:

Table : 8 Microscopic examination:

Urine culture and sensitivity test: no growth

Stool culture and sensitivity test: no enteric bacterial pathogen isolated

Ultrasonography reports:

-mild hepatosplenomegaly with increased echotexture of liver

-b/l kidney- bulky with increased echotexture and loss of CMD- likely s/o renal parenchymal diseases with RI values less than 0.8

-wedge shaped hypodensity seen in upper poles of right kidney? infract

-minimal interbowel loop fluid.

The patient was diagnosed with atypical hemolytic uremic(aHUS) syndrome. The patient underwent a detailed clinical examination including assessment of vital signs, systemic examination, physical examination, neurological examination, peripheral blood smear, hematological investigations, routine urinalysis, ASLO test, USG of abdomen, urine and stool culture and sensitivity test. The vital signs and anthropometry were normal, on physical examination pallor and icterus was seen. In systemic examination the tenderness was present in right upper quadrant, neurological examination showed mild weakness with normal reflexes. The low hemoglobin level with marked LDH and peripheral blood smear raised suspicion of hemolytic anemia. Whereas elevated urea, creatinine, abnormal LFT and USG report demonstrated significant renal involvement, the arterial blood gas investigation showed metabolic acidosis these findings were considered supportive of the patient systemic and renal dysfunction. In view of the combination of anemia, thrombocytopenia, biochemical evidence of hemolysis (elevated LDH, indirect bilirubin, reticulocyte count) and renal dysfunction, a thrombotic microangiopathy was suspected. HUS was considered as differential diagnosis. Urine and stool culture sensitivity and ASLO test were negative for an infectious etiology making typical HUS less likely. The clinical presentation, laboratory evidence of TMA and predominant renal involvement subsequently supported the diagnosis of atypical hemolytic uremic syndrome after exclusion of other causes of TMA. For treatment four sessions of dialysis were performed to manage AKI and patient developed severe HTN after first dialysis hence he was treated with tablet nefidipine and later titrated and shifted to tablet amlodipine when BP subsequently shows decreasing trends. plasmapheresis was done to which patient responded well hence continued the same treatment. Other medications such as paracetamol, emeset, calcium, multivitamins, were given as supportive therapy.

Table : 9 Treatment chart: