What Exactly Is Happening to My Kidneys?
Understanding Kidney Disease
How your kidneys work, what happens when they become damaged, and why early understanding matters.
Section 1 – What Your Kidneys Do
Large Illustration of Healthy Kidneys
Healthy kidneys help:
- Filter waste from your blood
- Remove excess fluid from your body
- Balance electrolytes and minerals
- Help control blood pressure
- Produce hormones that support important body functions
- Support healthy bones
- Help make red blood cells
Section 2 – What Happens When My Kidneys Become Damaged?
Kidney disease can cause:
- Waste products build up in the blood
- Excess fluid can build up in the body
- High blood pressure may worsen or develop
- Anemia (low red blood cell count)
- Bone disease and mineral imbalances
- Swelling in the feet, legs, hands, or face
- Fatigue and decreased energy
Section 3 – Common Causes of Kidney Disease
Common causes include:
- Diabetes
- High blood pressure
- Glomerular disease
- Polycystic kidney disease
- Lupus
- Recurrent kidney infections
- Certain medications
- Family history of kidney disease
✔ Obesity
Section 4 – Risk Factors: Simple Checkup
✔ Diabetes
✔ High blood pressure
✔ Heart disease
✔ Smoking
✔ Family history of kidney disease
✔ Age
People in the following groups have a higher risk of developing kidney disease:
✔ African Americans
✔ Hispanics
✔ Native Americans
✔ Some Asian populations
Section 5 – Can Kidney Disease Be Slowed?
Taking these steps may help slow the progression of kidney disease:
- Control your blood pressure
- Manage diabetes effectively
- Eat a kidney-friendly, healthy diet
- Stay physically active through regular exercise
- Take your medications exactly as prescribed
- Avoid NSAID medications unless directed by your healthcare provider
- Keep all scheduled medical appointments
Section 6 – When Should You Call Your Doctor?
Warning signs include:
- Rapid swelling
- Chest pain
- Difficulty breathing
- Blood in your urine
- A sudden decrease in urine output
- Severe swelling
- Needing to sleep sitting up or being unable to lie flat because of shortness of breath
Knowledge Empowers. Early Action Protects Kidney Function.
Understanding Your Lab Tests
What Your Blood Tests Are Telling You
Your laboratory tests provide important information about how well your kidneys are working and how kidney disease is affecting the rest of your body. Learning what these numbers mean can help you better understand your condition, ask informed questions, and actively participate in your healthcare.
What You’ll Learn on This Page
- Why Lab Tests Are Important
- The Most Common Kidney Blood Tests
- Understanding Creatinine
- Understanding eGFR (Estimated Glomerular Filtration Rate)
- Understanding BUN (Blood Urea Nitrogen)
- Understanding Potassium, Sodium, and Phosphorus
- Understanding Calcium and Parathyroid Hormone (PTH)
- Understanding Hemoglobin and Anemia
- Understanding Albumin and Nutrition
- Understanding Urine Tests and Protein
- Questions to Ask Your Healthcare Provider
Section 1 – Why Are Lab Tests Important?
Your laboratory tests help your healthcare team monitor your kidney function, detect changes early, guide treatment decisions, and identify potential complications before they become serious.
Although a single test result provides useful information, your healthcare team looks for trends over time rather than relying on a single number. Monitoring these trends helps your providers better understand how your kidneys are functioning and whether your treatment plan is working effectively.
Creatinine
What does it measure?
Creatinine is a waste product produced by normal muscle activity. Healthy kidneys remove creatinine from the bloodstream. As kidney function declines, the creatinine level in the blood usually increases.
Creatinine levels can also be affected by muscle mass, diet, medications, hydration, and other health factors. For that reason, healthcare providers usually review creatinine together with other kidney test results.
eGFR
Estimated Glomerular Filtration Rate
What does it help explain?
The eGFR estimates how well your kidneys are filtering waste from your blood.
It can help explain:
- What your kidney-function level means: A higher eGFR generally indicates better kidney filtration, while a lower eGFR may indicate reduced kidney function.
- Why the number matters: Healthcare providers use eGFR, along with other test results, to help identify and monitor kidney disease.
- Why it may change over time: Your eGFR may change because of kidney function, hydration, illness, medications, or changes in your creatinine level.
An eGFR is an estimate rather than an exact measurement. One result alone may not provide the full picture, so healthcare providers often compare results over time.
BUN
Blood Urea Nitrogen
What does it help explain?
BUN measures the amount of urea nitrogen in your blood. Urea is a waste product created when your body breaks down protein.
It can help explain:
- How much waste is present in your blood: A higher BUN level may mean that more urea is remaining in the bloodstream.
- How well the kidneys are removing urea: The kidneys normally filter urea from the blood and remove it through urine.
- How hydration may affect the result: Dehydration can raise the BUN level, while excess fluid may sometimes lower it.
BUN can also be affected by diet, medications, bleeding, illness, and other health conditions. Healthcare providers usually interpret BUN
together with creatinine, eGFR, and other test results.
Potassium
What does it help explain?
Potassium is a mineral that helps the nerves and muscles function properly, including the heart muscle. Healthy kidneys help maintain the correct amount of potassium in the blood.
Potassium results can help explain:
- Heart rhythm: Potassium levels that are too high or too low can interfere with the heart’s normal rhythm.
- Why abnormal potassium can be dangerous: A high potassium level may cause muscle weakness, an irregular heartbeat, or serious heart problems. A very low potassium level can also affect the muscles and heart.
- What may affect potassium levels: Certain foods, medications, diabetes, illness, dialysis, and changes in kidney function can affect potassium levels.
Important note: Not everyone with kidney disease needs to restrict potassium. Food choices should be based on laboratory results and guidance from a healthcare provider or kidney dietitian.
Phosphorus
What does it help explain?
Phosphorus is a mineral that works with calcium and vitamin D to support healthy bones and other important body functions. Healthy kidneys remove extra phosphorus from the blood.
Phosphorus results can help explain:
- Bone health: Too much phosphorus in the blood may pull calcium from the bones and weaken them over time.
- Kidney function: As kidney function declines, phosphorus may build up because the kidneys have more difficulty removing it.
- Diet and medication needs: Food choices, phosphorus additives, dialysis treatments, and prescribed phosphorus binders may affect phosphorus control.
Healthcare providers usually review phosphorus together with calcium, vitamin D, and parathyroid hormone levels.
Calcium and Parathyroid Hormone (PTH)
What do these results help explain?
Calcium is an important mineral that supports the bones, muscles, nerves, and heart. Parathyroid hormone, commonly called PTH, helps regulate calcium and phosphorus levels in the body.
The kidneys also help activate vitamin D, which allows the body to absorb and use calcium properly. When kidney function declines, this balance may be disrupted.
These results can help explain:
- Bone health: Abnormal calcium, phosphorus, and PTH levels may cause the bones to become weak or more likely to fracture.
- Vitamin D balance: Damaged kidneys may have difficulty activating vitamin D, which can affect calcium absorption and bone strength.
- Secondary hyperparathyroidism: When calcium levels are low or phosphorus levels are high, the parathyroid glands may produce too much PTH. Over time, elevated PTH can contribute to bone and mineral problems.
Healthcare providers usually interpret calcium, phosphorus, vitamin D, and PTH results together rather than relying on one result alone.
Hemoglobin
What does it help explain?
Hemoglobin is a protein inside red blood cells that carries oxygen throughout the body. A low hemoglobin level may indicate anemia, which is common in people with chronic kidney disease.
Hemoglobin results can help explain:
- Anemia: A low hemoglobin level means the blood may not be carrying enough oxygen to the body’s tissues.
- Fatigue and weakness: Anemia may cause tiredness, weakness, shortness of breath, dizziness, headaches, or difficulty concentrating.
- Why anemia is common in kidney disease: Healthy kidneys produce a hormone called erythropoietin, or EPO, that tells the body to make red blood cells. Damaged kidneys may produce less EPO. Iron deficiency, inflammation, blood loss, and other health conditions may also contribute to anemia.
Healthcare providers may review hemoglobin along with iron studies and other laboratory results to determine the possible cause and appropriate treatment.
Albumin
What does it help explain?
Albumin is a protein made by the liver and found in the blood. It helps keep fluid inside the blood vessels and carries hormones, vitamins, medications, and other substances throughout the body.
Blood albumin results can help explain:
- Nutrition and protein intake: A low albumin level may sometimes be associated with poor nutrition or inadequate protein intake.
- Inflammation or illness: Infection, inflammation, liver disease, and other medical conditions may lower blood albumin levels.
- Protein loss and fluid balance: Albumin may be lost through damaged kidney filters. A low blood albumin level may also contribute to swelling because fluid can move out of the blood vessels and into surrounding tissues.
A low albumin level does not always mean that a person is not eating enough protein. Healthcare providers consider diet, inflammation, liver function, urine protein loss, fluid balance, and other laboratory results when interpreting albumin.
Urine Protein
What does it help explain?
Healthy kidneys keep most protein in the bloodstream. When the kidneys’ filtering units are damaged, albumin or other proteins may leak into the urine.
Urine protein may be measured through a urine albumin-to-creatinine ratio, also called a UACR, or through other urine protein tests.
Urine protein tests can help explain:
- Protein leakage: Protein in the urine may show that the kidneys are allowing albumin or other proteins to pass through their filters.
- Possible kidney damage: An elevated urine albumin or protein result may be an early sign of kidney damage, even when other kidney-function results appear normal.
- Why reducing protein loss matters: Persistent protein loss may be associated with worsening kidney disease and a higher risk of heart and blood-vessel problems. Treatment of blood pressure, diabetes, and other underlying conditions may help reduce protein loss in some patients.
Healthcare providers often repeat urine testing and monitor the results over time because temporary factors—such as dehydration, fever, infection, strenuous exercise, or uncontrolled blood sugar—may affect the result.
This information is consistent with patient-education guidance from the National Kidney Foundation and the National Institute of Diabetes and Digestive and Kidney Diseases.
Questions to Ask Your Healthcare Provider
- What do my lab results mean?
- Which numbers should I watch most closely?
- Are my results improving or worsening?
- What can I do to improve them?
- How often should my lab work be checked?
- Should my medications or diet change?
Knowledge Grows with Understanding
Every lab result is another opportunity to take charge of your kidney health.
