Just to go through the parts of the labwork you mentioned - but know that it is challenging to interpret the results without seeing the full labwork and clinical history:
ALT. (sgpt). 112
ALT is a liver enzyme, which is an indicator of liver cell injury. That injury can occur due to many reasons, one of which is pancreatitis. Each lab has its own reference range, but in any case this is a normal to only very mildly elevated value. It must be interpreted in conjunction with the other liver enzymes and bilirubin.
This is a kidney value. It is rare to come across a 20 year-old cat with fully functioning kidneys, so a mild BUN elevation like this is not surprising. Kidney disease can be a cause of loss of appetite and weight loss.
Precision psl. 42
This is a measure of pancreatic inflammation. An elevation is suggestive of pancreatitis, if clinical signs such as vomiting, weight loss, and inappetence are seen. However it is not always diagnostic for pancreatitis as nearby inflammation, e.g. in the adjacent intestine can also cause this to appear elevated.
Lymphocytes are a type of white blood cell. A slightly low count like this is fairly unremarkable.
Eosinophils are another type of white blood cell, and this is a mild elevation. In a younger cat I would consider an elevation to be almost always either due to allergic or parasitic disease. In older cats we also have to add other disorders such as hyperthyroidism and cancer to the list.
I would strongly encourage an abdominal ultrasound, in particular to assess the pancreas, intestines, liver, and kidneys. This will give the vet the clearest picture of what is going on internally, and therefore best direct treatment.
I am assuming the suggestion of parasites came from the slightly elevated eosinophils. Consider testing a faecal sample for parasites to help rule this out. Does your cat ever go outdoors? If so, then having her empirically dewormed would also be reasonable.
Pancreatitis is a challenging disorder to treat but if appropriately managed can carry a good prognosis. The treatment can consist of:
- Fluids, to make sure the pancreas is well perfused. These can be given subcutaneously or intravenously, based on the severity of the case.
- Anti-nausea medication, such as Cerenia (maropitant) can help manage the signs of pancreatitis such as vomiting. Maropitant can also help with reducing pancreatic inflammation.
- Pain medication, as we often think pancreatitis can be a source of significant abdominal pain which can lead to further loss of appetite. Transmucosal buprenorphine is a good option in cats.
- Appetite stimulant, such as mirtazapine, if needed.
- Antacids, such as famotidine, in some cases.
- Diet can help - my personal favourite for pancreatitis is a gastrointestinal diet such as Hill's i/d, however you also have to consider other concurrent conditions, and it may be that a kidney diet is more vital.
I rarely turn to antibiotics for pancreatitis (it is almost always a sterile process in cats).
I also do not often turn to steroids as a first line treatment for pancreatitis, although it so happens that many of my pancreatitis patients are on steroids for other concurrent conditions such as inflammatory bowel disease or intestinal lymphoma. Steroids such as prednisolone can be great for controlling inflammation, but they have to be used judiciously.
Be aware that some cases of pancreatitis can be managed with minimal treatment, while others require aggressive use of fluids and medications to successfully treat.