Chronic Kidney Disease: Symptoms, Causes & What Every Patient Should Know

Overview

Chronic kidney disease (CKD) is a condition in which the kidneys are damaged and gradually lose their ability to filter waste from the blood. This damage develops over months or years, and in many cases, people don't realize anything is wrong until the disease has advanced significantly. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), CKD affects approximately 1 in 7 American adults — an estimated 37 million people — and most of them don't know they have it.

Your kidneys do far more than produce urine. Each day, they filter about 200 quarts of blood, removing waste products and excess fluid. They help regulate your blood pressure, balance minerals like sodium, potassium, and phosphorus, produce hormones that stimulate red blood cell production, and convert vitamin D into its active form so your body can use it. When the kidneys stop working well, every one of these functions is affected.

Early detection is critical. In the first and second stages of CKD, most people feel completely normal. Blood and urine tests are the only way to catch the disease early — which is why regular checkups matter, especially if you have diabetes, high blood pressure, or a family history of kidney disease.

Symptoms of Chronic Kidney Disease

Why Symptoms Appear Late

Symptoms of CKD develop slowly, and many people have none at all in the early stages. The kidneys have significant reserve capacity — they can lose a substantial portion of their function before the body begins to signal that something is wrong. By the time symptoms appear, kidney function is often already seriously impaired.

As the Mayo Clinic notes, symptoms are also frequently vague and can resemble those of many other conditions. This is one reason CKD is so often diagnosed only after routine blood work raises a red flag.

Symptoms of Advanced CKD

When CKD progresses to the later stages, the following symptoms may develop:

• Nausea and vomiting — Waste buildup in the blood (uremia) can cause persistent nausea and, in some cases, vomiting.
• Loss of appetite — A buildup of toxins and changes in taste can reduce the desire to eat, which can lead to unintentional weight loss.
• Fatigue and weakness — Anemia (low red blood cell count) caused by reduced kidney hormone production leads to persistent tiredness that rest doesn't fix.
• Sleep problems — Discomfort, restless legs, and other factors related to toxin buildup can make it difficult to fall or stay asleep.
• Decreased mental sharpness — Trouble concentrating, difficulty making decisions, and memory lapses can occur as toxins accumulate in the bloodstream.
• High blood pressure that's difficult to manage — As kidney function declines, the body retains more salt and water, raising blood pressure and creating a damaging cycle.
• Shortness of breath — Fluid can accumulate in the lungs (pulmonary edema), making breathing labored, especially when lying down.
• Swelling in the feet and ankles — Fluid retention causes visible puffiness in the lower extremities.
• Dry, itchy skin — Phosphorus imbalances and reduced kidney filtering contribute to skin dryness and persistent itching.
• Muscle cramps — Electrolyte imbalances, particularly low calcium and high phosphorus, can trigger painful muscle cramps.
• Urinating too much or too little — Some people urinate more frequently, especially at night. In advanced stages, urine output may decrease significantly.

Because these symptoms can have many causes, they do not automatically mean you have CKD. However, if you are at risk or experiencing several of these symptoms together, a blood test and urine test are the appropriate next steps. Do not wait for symptoms to worsen before speaking with your doctor.

CKD Stages

Understanding eGFR

CKD is classified into five stages based on a blood test called the estimated glomerular filtration rate (eGFR). This test measures how much blood your kidneys filter each minute, expressed in milliliters per minute (mL/min). A lower eGFR number means your kidneys are working less efficiently.

Your healthcare team may also test for protein in your urine (albuminuria), which is another marker of kidney damage. Together, eGFR and urine albumin levels give a clearer picture of where you are in the disease.

Stages 1 and 2 often have no symptoms and are frequently discovered incidentally. By Stage 3, some patients begin to notice fatigue or changes in urination. Stages 4 and 5 carry the highest risk of serious complications, including the potential need for dialysis or a kidney transplant.

Keto Nephron™ DS (NephLong) is a medical food formulated specifically for the dietary management of CKD stages 3–5, for use under the supervision of a physician — the stages where dietary management becomes an increasingly important part of the overall care plan.

What Causes Chronic Kidney Disease

How Kidney Damage Happens

CKD occurs when a disease or ongoing condition damages the kidneys over time. The kidneys filter blood through millions of tiny filtering units called nephrons. When these are repeatedly damaged — by high blood sugar, high blood pressure, inflammation, or other stressors — they scar and lose function permanently. CKD often has more than one cause working simultaneously.

Common causes include:

Type 1 and Type 2 Diabetes

Diabetes is the leading cause of CKD in the United States. High blood glucose levels damage the small blood vessels in the kidneys over time, reducing their filtering capacity. People with poorly controlled diabetes are at especially high risk of progressing to later stages of CKD.

High Blood Pressure (Hypertension)

Elevated blood pressure is both a cause and a consequence of CKD. Sustained high pressure damages the walls of blood vessels throughout the kidneys, gradually impairing function. Managing blood pressure tightly is one of the most important steps in slowing kidney damage.

Autoimmune Diseases

Conditions like lupus, IgA nephropathy (a disease in which the immune system deposits proteins in the kidney's filtering structures), and sarcoidosis can trigger inflammation inside the kidneys that leads to chronic damage.

Polycystic Kidney Disease (PKD)

PKD is an inherited condition in which fluid-filled cysts grow in both kidneys over time, gradually replacing normal tissue. It is one of the most common genetic causes of kidney failure.

Prolonged Urinary Tract Obstruction

Blockages that prevent urine from leaving the kidneys — caused by an enlarged prostate, kidney stones, bladder tumors, or urinary tract cancers — can back up pressure into the kidney tissue and cause lasting damage.

Vesicoureteral Reflux

This condition causes urine to flow backward from the bladder up into the ureters and kidneys. Repeated episodes of urine reflux can lead to infections and scarring over time.

Long-Term Use of Certain Medications

Sustained use of nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen, as well as medications like lithium and certain immunosuppressants, can damage kidney tissue over months or years. Always use these medications only as directed and inform your doctor if you use them regularly.

Risk Factors for CKD

Several factors raise the likelihood that a person will develop CKD. Some cannot be changed; others can be managed. The NIDDK identifies the following as significant risk factors:

• Diabetes — The single strongest modifiable risk factor
• High blood pressure — Often co-occurs with diabetes and compounds kidney stress
• Heart disease — Reduced cardiac output affects blood flow to the kidneys
• Smoking — Reduces blood flow to the kidneys and accelerates damage
• Being overweight or obese — Excess body weight raises blood pressure and increases diabetes risk
• Race and ethnicity — Black, Native American, and Asian American individuals have a statistically higher prevalence of CKD
• Family history of kidney disease — Genetic predisposition plays a meaningful role
• Structural kidney abnormalities — Present from birth or developed over time
• Older age — Kidney function naturally declines with age, even without disease
• Frequent use of NSAIDs or other nephrotoxic medications — Repeated exposure increases cumulative risk
• If you have multiple risk factors, your physician may recommend more frequent monitoring — typically every 6 to 12 months — even if you feel well.

Complications of Chronic Kidney Disease

Because the kidneys regulate so many body systems, their decline affects nearly every organ. Understanding these complications can help you and your care team stay ahead of them.

High Blood Pressure

As damaged kidneys lose their ability to remove excess salt and water, blood pressure rises. Higher blood pressure then accelerates kidney damage further — a cycle that must be actively managed with medication and lifestyle changes.

Acidosis (Acid Buildup)

Healthy kidneys remove excess acid from the body. When they can't, acid accumulates in the blood. This metabolic acidosis can affect bone health by drawing calcium from bones and can also impair protein metabolism.

Fluid Retention

The kidneys' reduced ability to excrete water leads to swelling in the legs and ankles, and in more advanced cases, fluid can accumulate in the lungs (pulmonary edema), causing dangerous shortness of breath.

Hyperkalemia (High Potassium)

When kidneys can't effectively remove potassium, blood potassium levels rise. Hyperkalemia is potentially life-threatening because it can disrupt the heart's electrical activity. It most commonly becomes a concern in Stages 4 and 5.

Anemia

The kidneys produce erythropoietin, a hormone that signals the bone marrow to make red blood cells. Damaged kidneys produce less of this hormone, leading to anemia — a major contributor to fatigue in CKD patients.

Heart Disease

CKD accelerates arterial stiffening and calcification, significantly raising the risk of heart attack, heart failure, and stroke. According to the National Kidney Foundation, cardiovascular disease is the leading cause of death in people with CKD.

Weak Bones

Impaired kidneys fail to activate vitamin D and lose the ability to regulate phosphorus and calcium. This mineral imbalance weakens bones over time, raising the risk of fractures.

Sexual Health Concerns

CKD can reduce libido, cause erectile dysfunction in men, and affect fertility in women through hormonal disruptions tied to kidney function decline.

Central Nervous System Effects

In advanced CKD, toxin accumulation can impair concentration, cause personality changes, and in severe cases contribute to encephalopathy. These cognitive effects typically appear in the final stages of the disease.

Immune System Changes

CKD weakens the immune response, making it harder to fight infections. This becomes particularly relevant in patients who also require immunosuppressive treatments.

Pericarditis

Inflammation of the pericardium — the membrane surrounding the heart — can occur in advanced CKD, causing chest pain and other cardiac symptoms.

Pregnancy Complications

CKD raises the risk of complications for both the mother and the developing baby, including preeclampsia, preterm birth, and accelerated kidney function decline. Women with CKD who wish to become pregnant should work closely with both a nephrologist and a high-risk obstetrician.

Nutrition and Dietary Management in CKD Stages 3–5

Why Nutrition Matters in CKD

Managing what you eat is one of the most important tools in a CKD care plan — particularly once you reach Stages 3 through 5. As kidney function declines, the body's ability to process certain nutrients changes significantly. What a healthy person's kidneys handle effortlessly becomes a burden on kidneys that are already struggling. Working closely with your nephrologist and a registered renal dietitian on your nutritional strategy is a core part of your medical management.

The Nutritional Challenges of CKD

People with CKD stages 3–5 face a complex set of dietary requirements that often seem to pull in opposite directions:

Protein

The kidneys must filter the waste products created when the body metabolizes protein. Too much protein increases that load. However, too little protein leads to muscle wasting and malnutrition. The right amount depends on your stage, whether you are on dialysis, your overall nutritional status, and your physician's guidance.

Phosphorus

Damaged kidneys cannot excrete phosphorus efficiently. High phosphorus levels pull calcium from bones and can lead to vascular calcification. Phosphorus is found in many protein-rich foods, dairy products, and processed foods — making it difficult to manage without specific dietary guidance.

Potassium

As discussed in the complications section, high potassium is a cardiac risk. Foods that are considered healthy for most people — bananas, oranges, potatoes, tomatoes — can be hazardous for someone in later-stage CKD.

Sodium

Excess sodium drives fluid retention and raises blood pressure. Limiting sodium is important across all stages of CKD and becomes increasingly critical as the disease advances.

Fluid Balance

In advanced CKD and particularly for patients on dialysis, fluid intake itself must often be controlled.

Standard grocery store foods — even those marketed as 'healthy' — are almost never calibrated to meet the precise nutritional needs of a person with CKD stages 3–5. This is where medical nutrition therapy (MNT), guided by a renal dietitian, plays a role. MNT involves an individualized nutrition assessment and an eating plan tailored to your labs, your stage, your medications, and your other health conditions.

Medical Foods and CKD

For patients in CKD stages 3–5, some nephrologists and renal dietitians work with patients to incorporate medical foods — products specifically formulated to meet the distinctive nutritional needs of a disease condition under physician supervision.

Keto Nephron™ DS (NephLong) is a medical food intended for the dietary management of chronic kidney disease (CKD) stages 3–5, for use under the supervision of a physician. It is formulated around the CKD-appropriate nutritional parameters that your nephrologist and renal dietitian establish as part of your individualized care plan. Keto Nephron™ DS (NephLong) is not a replacement for medical care, physician guidance, or a renal dietitian's expertise — it is designed to work within the nutrition framework your healthcare team defines for you.

Ask Your Care Team About Medical Nutrition

If you're in CKD stages 3–5, ask your nephrologist or renal dietitian whether a medical food like Keto Nephron™ DS (NephLong) may be appropriate as part of your individually tailored nutrition plan.

Prevention

While CKD cannot always be prevented — especially when genetic or structural factors are involved — there are meaningful steps that can reduce your risk or slow damage if kidney disease is already present.

Use OTC medications as directed.

Pain relievers like ibuprofen (Advil, Motrin) and naproxen (Aleve) are among the most common contributors to kidney damage when overused. Follow package instructions carefully, and let your doctor know if you rely on NSAIDs regularly. There may be kidney-safer alternatives for your pain management needs.

Maintain a healthy weight.

Excess body weight raises blood pressure and increases the risk of developing type 2 diabetes — the two leading causes of CKD. A healthy weight, achieved through a balanced diet and regular physical activity, significantly lowers long-term kidney risk.

Don't smoke.

Smoking reduces blood flow to the kidneys, raises blood pressure, and accelerates existing kidney damage. Quitting smoking is one of the most impactful steps a person with CKD risk factors can take. Your healthcare team can connect you with cessation support.

Manage diabetes, blood pressure, and heart disease.

These three conditions are the primary drivers of CKD progression. Working closely with your healthcare team to keep blood sugar, blood pressure, and cholesterol within target ranges directly protects your kidneys over time.

Stay hydrated — but appropriately so.

Adequate fluid intake supports kidney function, but excessive fluid intake is not beneficial and may be harmful in advanced CKD. Follow your physician's guidance on fluid targets.

Get regular lab monitoring.

For people at elevated risk, routine blood and urine tests — typically every 6 to 12 months — are the most reliable way to catch early changes in kidney function before they become serious. Early detection opens the door to earlier intervention.

When to See a Doctor

Who Should See a Nephrologist

If you have an ongoing condition — such as diabetes, high blood pressure, or an autoimmune disease — your primary care physician may already be monitoring your kidney function. But if tests reveal possible kidney problems, a referral to a nephrologist (a physician who specializes in kidney diseases) is typically the next step.

You should also speak with your doctor promptly if you experience any of the advanced symptoms described earlier, particularly significant swelling, persistent shortness of breath, or major changes in urination.

What to Expect

When your doctor evaluates kidney function, testing typically includes:

• eGFR blood test — Measures how efficiently your kidneys are filtering blood, using your creatinine level, age, sex, and race as inputs
• Urine albumin-to-creatinine ratio (uACR) — Detects even small amounts of protein in the urine, which is an early marker of kidney damage
• Kidney ultrasound — Assesses the size, structure, and visible characteristics of the kidneys; can identify cysts, stones, or blockages
• Additional imaging — In some cases, a CT scan or MRI may be used for more detailed evaluation
• Kidney biopsy — In select cases, a small tissue sample is taken to identify the specific cause of kidney disease

If you are already diagnosed with CKD and are being actively monitored, expect lab work every 3 to 6 months in later stages, and at minimum every 6 to 12 months in earlier stages.

Don't Wait for Symptoms

The most important takeaway: CKD is largely silent until it is advanced. Most people with early CKD feel completely well. Waiting for symptoms before seeking evaluation means waiting until significant kidney damage has already occurred. If you have risk factors — especially diabetes or high blood pressure — proactive monitoring is your single most effective tool.

A Final Word

Chronic kidney disease is serious, but it is not a sentence. Millions of people live full, active lives with CKD by working closely with their healthcare team, staying on top of their labs, and making informed choices about diet and lifestyle. The key is not to go it alone.

If you've been diagnosed with CKD — or if you're at risk — build a team that includes your primary care physician, a nephrologist, and a registered renal dietitian. Understand your stage, know your numbers, and ask questions at every appointment. Early detection and consistent management make a genuine difference in outcomes.

You are not powerless against this disease. With the right support and the right information, you can take meaningful steps to protect the kidney function you have.