What Causes Clay Coloured Stool In A 50 Year Old Woman?
Most likely hepatobiliary obstruction.
Detailed Answer:
Hello and welcome,
Clay colored stool is usually caused by a blockage in the biliary system, which you mentioned. I don't know how long it takes to get in to see an gastroenterologist in your area, but if it takes a while, then go in to see your primary care doctor who will (or should) order an ultrasound of the gall bladder, liver, and pancreas. That will help start to sort things out and can be diagnostic if there are "silent" gall stones. If gall stones block the outflow of bilirubin, that can cause the clay colored stools. It sometimes causes the urine to be dark, too.
About the Beta Thalassemia, it can cause an increased rate of gall stones. So this is something that would be worth looking into. Your primary doctor or gastroenterologist can order a Peripheral Smear. This is like a CBC, but not run through an automated machine - the lab staff actually look at the blood for abnormalities.
So that will give you something to get you started and may show the answer. I hope this information helps. Please let me know if I can provide further information or clarification.