When I think of my kidneys they do not seem particularly fabulous, like when I think of my heart or my brain or even my liver. I do know my kidneys are important because without them I would drown in my own body fluids. What a nightmare that would be! I gained much respect and admiration for all the things that my kidneys do for me when I worked as a dialysis nurse taking care of people who had lost their kidney function.
I learned that my kidneys do a lot more than just filter fluid out of my blood stream. It is marvelous that I have two kidneys and I can live a healthy life with just one of them. Each kidney has about 1 to 1 ½ million filtering units. Each of these units is called a “nephron” and does the marvelous work of filtering the wastes, extra fluids and electrolytes that would become toxic to my fragile physiology if they were not excreted. My kidneys are also busy with other jobs which include keeping my blood pressure normalized via the renin/angiotensin system and preventing anemia via their role in red blood cell formation. My kidneys keep my pH normal by maintaining my acid/base balance. They keep my bones healthy through the role they play balancing calcium and phosphorus in my body so I don’t end up with a fragile, porous skeleton. I thank my kidneys every day for the important roles that they play in my overall health and well-being.
If my kidneys fail to work properly, the filtration rate will drop and damage to the filtering membrane will allow protein to be filtered out of the blood. This protein will show up in my urine. (Albuminuria) The screening test to detect protein in urine is the urinary albumin-to-creatinine ratio (UACR) done with a random spot urine collection. This measures the presence of elevated urinary albumin (protein) excretion. Doing the time intensive 24 hour urine collection does not add any significant value to prediction or accuracy to the determination of what stage of kidney disease is occurring. A UACR of =/> 30 mg/g Cr is considered abnormal. Another test is the estimated glomerular filtration rate (eGFR), an additional marker of kidney function and disease. An eGFR of <60 mL/min/1.73 m2 is generally considered abnormal. Both of these tests vary in people over time and there are no studies that tell us what “normal” is for my kidney at 20 years of age versus what is normal for me at my current age of 65 years. There are some established guidelines for diagnosing chronic kidney disease based on eGFR with a UACR persistently =/>30mg/g Cr or other abnormalities on pathological, urine, blood or imaging tests.(Adapted from Levey et al.)
The stages of chronic kidney disease are defined according to the following:
1 Kidney damage with normal or increased eGFR of =/> 90
2 Kidney damage with mildly decreased eGFR of 60-89
3 Moderately decreased eGFR of 30-59
4 Severely decreased eGFR of 15-29
5 Kidney failure of <15 or dialysis
With diabetes, kidney damage can occur from chronically elevated blood glucose levels and/or the effects of uncontrolled high blood pressure. Diagnosis is made based on the presence of albuminuria and/or reduced eGFR without any signs or symptoms of disease, so it can be very sneaky. That is why screening is so important in people with diabetes. Generally, diabetic kidney disease develops after duration of 10 years with type 2 diabetes and as early as 5 years with type 1 diabetes. People with diabetic kidney disease almost always have diabetic retinopathy and/or cardiovascular disease as well.
I think everyone wants to have healthy kidneys so what can we do as educators to help our people with diabetes (PWD) take care of theirs?
- Recommend that they have an annual spot urinary albumin-to-creatinine ratio and estimated glomerular filtration rate. This applies to people who have had a diagnosis of type 1 diabetes for 5 years or more, in all persons with type 2 diabetes and all PWD who have comorbid conditions.
- Assist all PWD to optimize glucose control to reduce the risk or slow the progression of diabetic kidney disease.
- Assist all PWD to optimize blood pressure control to reduce the risk or slow the progression of diabetic kidney disease.
- In PWD not on dialysis with kidney disease, encourage dietary intake of protein of not more than 0.8 g/kg body weight per day and for patients on dialysis, higher levels of protein may be needed. Higher levels of protein intake, (greater than 20% of daily calories from protein) have been associated with increased albuminuria, more rapid kidney function loss and cardiovascular mortality and should be avoided. In short, those low carb, high protein diets are not good for the diabetic kidney.
- In non-pregnant PWD and hypertension, either an ACEI or an ARB is recommended for those with modestly elevated UACR (30-299 mg/g creatinine) and is strongly recommended for PWD with UACR =/> 300 mg/g creatinine and/or eGFR < 60 mL/min/1.73 m2.
- An ACEI or ARB is not recommended for the primary prevention of diabetic kidney disease in PWD who have normal blood pressure, normal UACR and normal eGFR.
- Promptly refer to a physician experienced in the care of kidney disease for uncertainty about the cause of the kidney disease, difficult management issues and/or rapidly progressing kidney disease.
There are renal replacement therapies if kidney function fails but they are really not any fun. The options include hemodialysis, peritoneal dialysis and transplant. These are not cures. Even with kidney transplant or pancreas/kidney transplant, anti-rejection medications need to taken for a lifetime and medical follow-up is a requirement for successful results. We play an essential role in educating our patients about the progressive nature of diabetic kidney disease, the kidney preservation benefits of proactive treatment of blood pressure and blood glucose, and the potential need for renal replacement therapy. Knowledge is power. We can help PWD keep their kidneys healthy!
Information and recommendations taken from Diabetes Care Standards of Medical Practice-2017
Colleen Karper, BSN, RN, CDE
Manager of Diabetes Education and Prevention at Kalispell Regional Medical Center in Kalispell, Montana.
January 20, 2017