Soon before I left NYC, my cat's diabetes became quite uncontrolled. His previously controlled blood glucose became consistently high, and could not be regulated, even with increasing doses of insulin. This is called insulin-resistance. While he didn't have "text-book" insulin resistance, I knew something was awry.
Diabetic cats' insulin requirements can dramatically increase when they have a concurrent illness. Things to rule out are: urinary tract infections (including pyelonephritis), chronic pancreatitis, hyperadrenocorticism (Cushing's), acromegaly (increased production of growth hormone), dental disease, heart disease, and different types of cancer.
So I brought him to the hospital where I was working, performed full-body radiographs: normal. Full CBC, chemistry, T4, urine cortisol-creatinine ratio, feline PLi, urinalysis, and urine culture - all perfectly normal. Hmm....
There was not a clue as to what was going on. While a little frustrated, I knew there was a strong possibility there was still something wrong with Isaac. When I returned to Toronto, I scheduled an ultrasound for him. The ultrasound showed mildly enlarged kidneys, consistent with pyelonephritis (I've already posted twice on this disease). Interestingly, and frustratingly, his previous urinalysis was completely normal - crystal clear - and his culture was negative; not a hint of an infection.
With chronic disease, though, this is still possible and therefore not a complete mystery.
I started Isaac on a 6-8 week course of antibiotics and so far, he's doing great.
Had I not performed the ultrasound, he would likely have deteriorated.
What are the lessons here? 1) To understand that tests are not always diagnostic - of course they can be - and that normal test results do not necessarily ruled out everything.
2) In many cases, further work-ups are necessary. After preliminary tests, this often (but not always) means imaging, such as x-radiography, ultrasound, MRI (magnetic resonance imaging) or CT (computed tomography).
3) Sometimes, even specialists (in medicine, too!), cannot achieve diagnoses - there are true mystery illnesses.
4) Follow your suspicions: in this case, there was some, but not overwhelming, evidence that Isaac was sick. I was most probably right.
Isaac's diagnosis of pyelonephritis is strongly suspected, but is still not confirmed. I am now both the client and the veterinarian, and will just have to be patient for now....
Will Isaac have to go back?