Protein loss and high blood pressure, as well as the features on biopsy of the kidney if performed, may predict progression to advanced kidney disease. Adults are more likely than children to develop advanced kidney disease. Pathophysiology
Henoch–Schönlein purpura is a small-vessel vasculitis in which complexes of immunoglobulin A (IgA) and complement component 3 (C3) are deposited on arterioles, capillaries, and venules (hence it is a type III hypersensitivity reaction). The activation of the alternative complement pathway results in the deposition of IgA aggregates or IgA complexes in target organs (with deposition of C3). This leads to the production of inflammatory mediators, including vascular prostaglandins like prostacyclin, which may play a key role in the development of IgAV and its organ-specific clinical manifestations. As with IgA nephropathy, serum levels of IgA are high in HSP and there are identical findings on renal biopsy; however, IgA nephropathy has a predilection for young adults while HSP is more predominant among children. Further, IgA nephropathy typically only affects the kidneys while HSP is a systemic disease. HSP involves the skin and connective tissues, scrotum, joints, gastrointestinal tract and kidneys. The genetic basis remains unclear except for involvement of the human leukocyte antigen region of the genome. It is hypothesized to involve autoimmunity triggered by infections. Streptococcus strains and Parainfluenza virus are the most commonly associated pathogens, and in children Human Parvovirus B19 is a frequent viral trigger

Diagnosis
The diagnosis is based on the combination of the symptoms, as very few other diseases cause the same symptoms together.
Sulfadiazine is an antibiotic. Used together with pyrimethamine, a dihydrofolate reductase inhibitor, it is the treatment of choice for toxoplasmosis, which is caused by a protozoan parasite. It is a second-line treatment for otitis media, prophylaxis of rheumatic fever, chancroid, chlamydia, and infections by Haemophilus influenzae. It is also used as adjunct therapy for chloroquine-resistant malaria and several forms of bacterial meningitis. It is taken by mouth. Sulfadiazine is available in multiple generic tablets of 500 mg. For urinary tract infections, the usual dose is 4 to 6 grams daily in 3 to 6 divided doses.Common side effects include nausea, diarrhea, headache, fever, rash, depression, and pancreatitis. It should not be used in people who have severe liver problems, kidney problems, or porphyria. If used during pregnancy, it may increase the risk of kernicterus in the baby. While the company that makes it does not recommend use during breastfeeding, use is believed to be safe if the baby is otherwise healthy. It is in the sulfonamide class of medications.Sulfadiazine was approved for medical use in the United States in 1941. It is on the World Health Organizations List of Essential Medicines. Sulfadiazine is available as a generic medication. Medical uses
It eliminates bacteria that cause infections by stopping the production of folate inside the bacterial cell, and is commonly used to treat urinary tract infections and burns. In combination, sulfadiazine and pyrimethamine can be used to treat toxoplasmosis, the disease caused by Toxoplasma gondii. Mechanism of action
Sulfadiazine works by inhibiting the enzyme dihydropteroate synthetase.