See Hyperoxaluria Prenatal Before birth. Pyridoxine is also known as Vitamin B6. High quantities are found in brewers yeast. Pyridoxine supplements are readily available. Renal refers to the kidneys.
Renal failure means kidney failure.
Snail Mail is techie for postal mail. Supersaturation is the state of a liquid containing more of a dissolved substance than is normal. In this case, the supersaturation refers to excessive amounts of oxalate and calcium in the urine. Thiamine is also known as Vitamin B1. This vitamin is found in many foods.