"But my labs are always normal" is the response that I usually hear from clients when I share with them how severe their eating disorder is. I have to admit that I truly expected to see horrible labs when I first started to evaluate eating disordered patients. Most of our clients have relatively normal lab work. This is often even true of clients that are engaging in severe eating disorder behaviors.
Every doctor knows to make sure to check electrolytes in someone that is purging. Low potassium levels can certainly occur and is a life threatening condition if severe enough. It's also important to know that a lab report is just a snapshot of that moment and can change instantly. A normal potassium level one day can be critically dropped with behaviors that cause dehydration.
Generally though, labs are normal. This occurs because the labs are mostly just ensuring that there isn't currently a shut down of the different organs such as the liver or kidneys. Routine labs don't really test for optimal vitamin status. For instance, a normal blood serum level of calcium doesn't mean that one has enough calcium in the diet to maintain bone health or for muscle relaxation. Essentially, the routine labs often just let me know if one is stable enough for residential care or if hospitalization is required.
So, when routine labs are normal I'll look for an elevation of liver enzymes that indicate liver damage, low iron storage levels and low blood sugar on their first day of treatment. Also, if indicated, I'll often order a DEXA scan to check bone density. It is the rare DEXA in eating disorder treatment that comes back normal. Sometimes this is the only medical proof that a client receives that shows damage.
There are specialty labs that do functional testing and can give me information about whether someone has deficits that are occurring as a result of an eating disorder. Clients commonly will have low amino acids if restricting protein or fat consumption. When performed, this type of lab can help to motivate healthy eating. A client can see the cause and effect of her eating disorder behaviors.
Physical exams can be revealing too. Poor circulation can be reflected in purple, cold toes. There is often swelling of the glands in the cheeks from purging. Some clients have extra hair growth resulting from low weight. Often we'll see a jump in heart rate with a change in position. Not all these signs are looked for in a routine examination.
As these issues improve, I will review the strides that a client has made to validate all the effort that she has been making. This could even be, "remember when you couldn't let yourself have fun". No lab can measure that.