Thursday, March 1, 2012

I hate DKA

One of my final patients on internal medicine last week was a sweet little kitty named Jewel.

Jewel's owner brought her to the VTH because for the last 6-8 weeks Jewel had been peeing a lot more than usual. Her owner also suspected Jewel had lost some weight during that same period of time.

Somewhat surprisingly, Jewel had never seen a vet except for when she was spayed. For an 8 year old cat, I wish I could tell you that was unusual -- but it's not. The surprising part is that, instead of taking Jewel to a regular general practice vet, she made a specialty appointment to see internal medicine. This is the type of presenting complaint that can often be handled easily or at least initially worked up by a GP, but hey, we were happy to see Jewel if that's what her owner wanted.

The top 3 differentials for a middle-aged to elderly cat with PU/PD (polyuria [urinating excessively] and polydipsia [drinking excessively]) +/- weight loss are (1) kidney disease, (2) hyperthyroidism, and (3) diabetes mellitus. Fortunately, all of those diseases can be ruled in or out pretty simply by doing a CBC, chemistry, urinalysis, and T4 (thyroid).

Which we did in Jewel's case, and which showed a blood glucose of almost 400 (normal is about 80-120, though upset cats can get up to about 300 just from the stress of being in the hospital) and 4+ glucose in her urine (normal = no glucose). These results, in combination with Jewel's clinical signs, were highly suspicious of diabetes. To confirm, we submitted a fructosamine measurement. This measures a type of protein that gets extra glucose added onto it when the blood sugar is very high for a prolonged period of time. Thus, you can get an assessment of how well a patient's diabetes is controlled during the last 2-3 weeks. Jewel's fructosamine was 790, with a normal cat's being 200-350!

Jewel's owner handled the diagnosis like a champ. The day after we ran the lab tests that diagnosed Jewel's diabetes, her owner returned with her for a lesson in giving insulin injections. At that second appointment, Jewel's owner mentioned that Jewel had seemed very stressed after the previous day's visit and had hid in her carrier all night -- extremely unusual behavior for Jewel. We were not surprised, given that Jewel had basically never been in a carrier, car, or to the vet before.

We sent Jewel home with twice-daily insulin, urine ketone/glucose monitoring strips, and a gradual diet change to a prescription diet for diabetes -- along with extensive client education about diabetes and how it is managed. The next day, however, Jewel's owner called to let us know that Jewel had refused to eat her last 2 meals and had been vomiting overnight. These are never good signs in any cat, and especially in a diabetic, so we of course recommended that she bring Jewel in right away.

Jewel arrived through Urgent Care shortly before we left for the day. She was very lethargic and dehydrated. Repeat bloodwork and urinalysis showed that Jewel was now in diabetic ketoacidosis (DKA). Also known as a "diabetic crisis," DKA occurs in a diabetic when the animal undergoes excessive stress or has another underlying disease process such as cancer or an untreated infection. The body becomes unable to utilize glucose appropriately, so starts breaking down other tissues as a food source. Ketones are produced as a result (the "keto" in diabetic ketoacidosis), and the patient's body because very acidotic (the "acidosis" in diabetic ketoacidosis). Acid-base balance (pH) is extremely crucial to survival. All of the enzymes that control every process in the body only function at a certain pH, so if the body becomes very acidotic, those enzymes can stop working, resulting in organ failure and death.

DKA can be an ugly, labor-intensive, and costly condition to treat. However, if the underlying disease process that kicked off the crisis can be discovered and treated, and if the owner can commit to a multiple-day stay in the hospital and potentially $2-5000, DKA is often treatable. Fortunately, Jewel's owners seem to be in it for the long haul.

Unfortunately, Jewel's case has another complicating factor. Because Jewel refused to eat for several days, she developed a secondary condition called hepatic lipidosis ("fatty liver disease"). Somewhat similar to DKA, hepatic lipidosis occurs when a cat is not eating, so the body utilizes fat stores. If this goes on for long enough, the liver gets overwhelmed by fatty deposits and becomes unable to function appropriately. The treatment for hepatic lipidosis is supportive care (which often means force-feeding, using a nasoesophageal tube, or an esophageal or gastric feeding tube), but even then some of these patients still die and we don't know why.

The good news is that Jewel seems to be improving, after 5-6 days in the hospital. She still doesn't want to eat but has been getting some nutrition from a tube placed through her nostril into her esophagus.

The bad news is that Jewel's primary clinician and I both feel terrible about her developing DKA. We have blood and urine results from Jewel's first visit that prove that Jewel was not in DKA at that time -- her pH balance was normal and there were no ketones in her urine. But when she came back 2 days later, inappetant and vomiting, she was absolutely in DKA as evidenced by huge changes in her labwork.

The frustrating part is that the massive stress alone from Jewel's first visit (where we ran the initial diagnostics that revealed her diabetes) was probably enough to kick her into DKA. Once we diagnosed her DKA, we went on a "hunt" for an underlying cause, including other lab tests, ultrasounds, and x-rays, but found nothing. I feel bad that we didn't have a suspicion of underlying illness on Jewel's second visit to us, when we showed her owner how to give insulin shots and she mentioned that Jewel had hid in her carrier all night. However, I doubt there would have been much we could have done differently at that point anyway, other than potentially catch Jewel's DKA a day earlier -- though that probably wouldn't have changed the outcome.

This case was very educational for me (as was almost every case I saw on internal medicine -- one of the benefits of that service!). It taught me a lot about the initial management of a newly diagnosed diabetic, as well as treatment of DKA. And, especially, it taught me never to underestimate the sensitivity of a diabetic patient to stress and illness, and not to assume that a patient's odd behavior can be attributed solely to a known stressful event the day before.

1 comment:

  1. Hahaha I'm afraid I burst out laughing when I read "it taught me never to underestimate the sensitivity of a diabetic patient to stress and illness."

    Probably not a laughing matter, but it hit close to home. ;)

    ReplyDelete