are there any posions or toxins that may cause pnh?

PNH (Paroxysmal nocturnal hemoglobin) is a rare disease in which red blood cells break down earlier than normal.

Individuals with this disease have blood cells that are missing a gene called PIG-A. This gene allows a substance called glycosyl-phosphatidylinositol (GPI) to help certain proteins to stick to cells.
Without PIG-A, important proteins cannot connect to the cell surface and protect the cell from substances in the blood called complement.

As a result, red blood cells break down too early. The red blood cells leak hemoglobin into the blood, which can pass into the urine. This can happen at any time, but is more likely to occur during the night or early morning.
There is no known way to prevent this disorder.

I hope this answers your question.

Maryann