Membranous glomerulonephritis (MGN) is a slowly progressive disease of the kidney affecting mostly people between ages of 30 and 50 years, usually white people (i.e., those of European, Middle Eastern, or North African ancestry.). It is the second most common cause of nephrotic syndrome in adults, with focal segmental glomerulosclerosis (FSGS) recently becoming the most common. Signs and symptoms
Most people will present as nephrotic syndrome, with the triad of albuminuria, edema and low serum albumin (with or without kidney failure). High blood pressure and high cholesterol are often also present. Others may not have symptoms and may be picked up on screening, with urinalysis finding high amounts of protein loss in the urine. A definitive diagnosis of membranous nephropathy requires a kidney biopsy, though given the very high specificity of anti-PLA2R antibody positivity this can sometimes be avoided in patients with nephrotic syndrome and preserved kidney function

Causes
Primary/idiopathic
85% of MGN cases are classified as primary membranous glomerulonephritis—that is to say, the cause of the disease is idiopathic (of unknown origin or cause). This can also be referred to as idiopathic membranous nephropathy.One study has identified antibodies to an M-type phospholipase A2 receptor in 70% (26 of 37) cases evaluated.
Risk Factors and genetics
An elevated risk of developing tertiary hyperparathyroidism exists when late stage kidney disease is not corrected timely. This is due to a hyperphosphatemia acting directly on the parathyroid glands. Genetically, those who have an X-linked dominant disorder that disrupts phosphate transport at the renal tubules (X-Linked hypophosphatemic rickets) and are receiving oral phosphate treatment have shown to be at high risk of developing tertiary hyperparathyroidism in the absence of secondary hyperparathyroidism. Recurring tertiary hyperparathyroidism is generally seen to be caused by incomplete parathyroidectomy without renal transplant and the risk is increased when the parathyroid tissue left after surgery is that of a nodular type.Other risk factors of tertiary hyperparathyroidism include an elevated risk of developing acute pancreatitis, mainly due to the hypercalcemia associated with the hyperparathyroidism. Other studies have shown a significant increase in the risk of developing malignancies of the urinary tract and renal system with women being more at risk. Though there is some conjecture as to the correlation between hyperparathyroidism and thyroid carcinoma development, there is however a correlation between the two, which is thought to be due to prolonged irradiation of the neck and head for parathyroid adenomas and increased parathyroid hormone.Other studies have found some correlation in the development of renal disease following parathyroidectomy. However, the mechanism for this effect remains unknown. Pathophysiology
Tertiary Hyperparathyroidism is almost always related to end stage kidney disease and a secondary hyperparathyroidism. Physiological changes due to the kidney damage adversely affect feedback loops that control secretion of parathyroid hormone.