The nephrology office called this morning; they want me to come back next week to give a urine sample to see how I’m doing on Farxiga.
I finally went to the main web page at AstraZeneca and read about it. Interestingly, it tells how it’s for "Chronic Kidney Disease", but it doesn’t say *what kind* of disease. All of them, apparently. And there’s a warning "Do not take FARXIGA if you are allergic to dapagliflozin or any of the ingredients in FARXIGA." Okay, but I haven’t been able to find a list of those ingredients.
Essentially, Farxiga looks like a diabetes control drug. I don’t have diabetes.
Among the listed side effects:
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* Serious urinary tract infections (UTI), some that lead to hospitalization, occurred in people taking FARXIGA. Tell your healthcare provider if you have any signs or symptoms of UTI including a burning feeling when passing urine, a need to urinate often, the need to urinate right away, pain in the lower part of your stomach (pelvis), or blood in the urine with or without fever, back pain, nausea, or vomiting* Bacterial infections under the skin of the genitals and areas around them. Rare but serious infections that cause severe tissue damage under the skin of the genitals and areas around them have happened with FARXIGA. This infection has happened in women and men and may lead to hospitalization, surgeries, and death. Seek medical attention immediately if you have fever or you are feeling very weak, tired or uncomfortable and you also develop any pain or tenderness, swelling, or redness of the skin in the genitals and areas around them
* Yeast infection of skin around the penis (balanitis) in men who take FARXIGA. Talk to your healthcare provider if you experience redness, itching, or swelling of the penis; rash of the penis; foul smelling discharge from the penis; or pain in the skin around penis. Certain uncircumcised men may have swelling of the penis that makes it difficult to pull back the skin around the tip of the penis
The most common side effects of FARXIGA include yeast infections of the vagina or penis, and changes in urination, including urgent need to urinate more often, in larger amounts, or at night.
Actual information about the drug is buried in PDFs. "FARXIGA Full Prescribing Information.pdf" says:
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FARXIGA is a sodium-glucose cotransporter 2 (SGLT2) inhibitor indicated:• To reduce the risk of sustained eGFR decline, end stage kidney disease, cardiovascular death, and hospitalization for heart failure in adults with chronic kidney disease at risk of progression.
• To reduce the risk of cardiovascular death, hospitalization for heart failure, and urgent heart failure visit in adults with heart failure.
• To reduce the risk of hospitalization for heart failure in adults with type 2 diabetes mellitus and either established cardiovascular disease or multiple cardiovascular risk factors.
• As an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
My blood sugar moved up from mid-90s to mid-teens on keto; that’s normal, and still okay. I had a full cardiac checkup last year, no problems. So the only possible thing would be "eGFR".
Further in the document, I find:
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——————— DOSAGE AND ADMINISTRATION ————————————-
• Assess volume status and correct volume depletion before initiating. (2.1)
eGFR (mL/min/1.73 m2)eGFR 45 or greater: To improve glycemic control, the recommended starting dose is 5 mg orally once daily. Dose can be increased to 10 mg orally once daily for additional glycemic control.
I never got the labs I asked for from my first visit, on 12/04/23. [slacking on follow-ups…] The last eGFR test I have results for was 10/03/23, from the urologist. That was 50. "Normal" is >59. I also have results from 07/20/21 (88) and 06/03/21 (92), a proteus UTI infection and follow-up after treatment. That was before I went on keto.
Okay, off to look up eGFR. According to the National Kidney Foundation web site, eGFR is :
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A calculation used to estimate how well your kidneys are filtering certain agents produced by your body, such as:creatinine (a waste product that comes from the normal wear and tear on muscles)
cystatin C (a protein that slows down the breakdown of other protein cells)
My GP freaked about my creatinine and C-Reactive Protein numbers after I went on keto; I took a couple of weeks off, re-tested, and everything looked fine. He was still unhappy about it, so he checks it every time I’m having blood work done.
Cystatin C was a new one to me. The Wikipedia page (yeah, whatever) says:
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Although studies are somewhat divergent, most studies find that cystatin C levels are less dependent on age, gender, ethnicity, diet, and muscle mass compared to creatinine,[13][14] and that cystatin C is equal or superior to the other available biomarkers in a range of different patient populations, including diabetic patients, in chronic kidney disease (CKD), and after kidney transplant.[15] It has been suggested that cystatin C might predict the risk of developing CKD, thereby signaling a state of ‘preclinical’ kidney dysfunction.[16] Additionally, the age-related rise in serum cystatin C is a powerful predictor of adverse age-related health outcomes, including all-cause mortality, death from cardiovascular disease, multimorbidity, and declining physical and cognitive function.[17] The UK’s National Institute for Health and Care Excellence (NICE) guideline for the assessment and management of CKD in adults concluded that using serum cystatin C to estimate GFR is more specific for important disease outcomes than use of serum creatinine, and may reduce overdiagnosis in patients with a borderline diagnosis, reducing unnecessary appointments, patient worries, and the overall burden of CKD in the population.[18]
Did he test for Cystatin C? I guess I’ll have to make another hour-plus trip to their office and get copies of the labs. [makes phone call] Looks like I’ll be driving down there *again*, third time this week. [sigh]
They’re supposed to have both labs plus the visit notes ready to pick up. I called the urologist’s office and they’ll have printouts of the last labs he did waiting for me; I have to pass near his office to get to the nephrologist.
Given some common side effects are the very problems I got on the referral-go-round to avoid, and my last eGFR number was above the drug manufacturer’s limit, and that eGFR is based on creatinine, which is out of range due to keto, I’m even less thrilled about taking Farxiga than I was before.