Chronic Kidney Disease (CKD)
Chronic kidney disease (CKD) is a degenerative disease of the kidneys. In addition to medication, CKD is managed nutritionally with diets that modify the intake of specific nutrients affected by impaired kidney function.
Chronic kidney disease (CKD) occurs when the kidneys' ability to filter and detoxify the blood is impaired, leading to the build up of waste products in the body. The condition generally gets worse over time, but progression can be stabilized and markers of the disease can be reversed in some instances. CKD affects 11–13% of the global population, and 14.0% of the United States population.
CKD does not usually present with any symptoms until kidney function is impaired by 50% or more. Symptoms include fatigue, confusion, brain fog, headaches, poor appetite, nausea, vomiting, poor sleep, nighttime muscle cramping, swelling in the feet and around the eyes, dry and itchy skin, and more frequent urination or lack of any urination.
Common signs of CKD include markers used for diagnosis — decreased GFR, decreased albumin, protein in the urine, elevated creatinine or cystatin — and markers of the underlying conditions — dyslipidemia, high blood pressure, glycemic dysregulation, and elevated uric acid levels.
In its early stages, CKD is a silent disease — there are usually no symptoms to warn that something may be going awry with the kidneys. Some experts recommend that people with risk factors for CKD (e.g., those with diabetes, hypertension, heart disease) receive yearly kidney function screenings.
CKD is diagnosed when kidney function tests show markers of serious kidney damage, e.g., decreased glomerular-filtration-rate (GFR) or creatinine, elevated ualbumin, or electrolyte abnormalities. Markers of kidney damage must persist over time to be labeled "chronic". CKD is classified based on GFR into 1 of 5 stages, where stage 1 is the least progressed disease state, and stage 5 represents kidney failure.  End-stage renal disease (ESRD) is defined as CKD stage 5 treated with dialysis.
CKD treatment includes strategies to manage impaired kidney function, to address the underlying cause, and to prevent any further kidney damage. For the majority of people with CKD, that means addressing heart disease, hypertension, and diabetes with medications, diet, and lifestyle changes. Treatment for CKD includes medications that lower blood pressure and block the renin-angiotensin-aldosterone system (RAAS). Other medications are used to manage uric acid levels, sodium levels, metabolic acidosis, blood lipids, blood glucose, and bone mineralization, and dialysis is used to externally purify the blood when the kidneys no longer function.
CKD compromises the kidneys’ ability to balance electrolytes and nutrients in the blood, so managing CKD involves limiting foods higher in sodium, phosphorus, and protein; supplementing or emphasizing foods high in calcium and vitamin-d to reach normal levels, and increasing total calories when a person is at risk for unintentional weight loss. potassium may be restricted or emphasized on an individual basis in order to maintain normal serum-potassium levels.
Studies on the effects of specific diets are sparse and short term, but show benefits to some markers of the disease. Studied diets include low-protein and very-low-protein diets, low-salt diets, low-fat diets, low-carbohydrate diets, high fruit-and-vegetable diets, plant-based diets, vegan , vegetarian diets, the Dietary Approaches to Stop Hypertension (DASH) diet, mediterranean-diet, American Heart Association diet, and American Diabetes Association diet.
The most common supplements studied for CKD are amino acid supplements used in conjunction with very-low-protein diets. Others include alkalizing therapy with potassium citrate salts, vitamin-d supplements, and omega-3 fatty acids supplements. Many other supplements have been investigated, including vitamin-e, antioxidant therapy, coenzyme-q10, n-acetylcysteine, bardoxolone methyl, and human recombinant superoxide dismutase, potassium, calcium fortification, nitrate, turmeric and boswellia, curcumin, vitamin-k, B vitamins, astragalus, cordyceps, and Rheum officinale.
No alternative modalities have been well studied for their use in managing CKD outcomes or symptoms. However, complementary modalities that promote general well-being by increasing physical activity and promoting stress reduction (acupuncture, mindfulness, tai chi, etc.) can be used to enhance well-being in people with CKD. A foundation of CKD treatment is managing conditions that cause CKD. Therefore, complementary approaches that benefit type-2-diabetes, hypertension, or heart disease may in turn benefit persons with CKD. Additionally, some modalities may help with feelings of depression and anxiety in people with CKD.
Diabetes, heart disease, and hypertension are the three most common diseases that lead to CKD. Some medications when used in excess or for prolonged periods (like chemotherapies and nonsteroidal anti-inflammatories) can cause CKD as well. Other causes of kidney damage that can lead to and/or worsen CKD include systemic infections, trauma or injury to the kidneys, congenital abnormalities, and autoimmune conditions.