The 5 W’s of Understanding Your Lab Results

Aug 14, 2021 | Tips and Tricks

As a kidney dietitian, I often have people come to me confused about their labs. At Happy Health Nutrition, I desire to help bridge the gaps in education that sometimes develop related to kidney disease. When your doctor recommends a renal function panel or other lab tests, you may start to have a lot of questions about these tests. It is normal; let’s break down the 5 W’s (Who, When, Why, What, and Where) so that you feel more confident about both the tests and beyond. 


It all starts with you and your doctor. It is essential that whichever doctor orders a blood draw that you always wait to hear their interpretations of the labs before jumping to conclusions. Most lab results take approximately 24 hours to result; however, some specialized tests can take longer as well as many times, results are not released to a person until a doctor has had a chance to see the results first. 

If you see your results before seeing your doctor, please remember that your doctor should interpret your results and follow the doctor’s recommendations. Kidney disease affects everyone at different rates, and each person’s health plan will be slightly different. If you have questions, call your doctor or their staff and ask.   


Why is your doctor ordering these tests in the first place? There are many reasons your doctor may choose to order a renal function panel. 

  1. Age- as we age, our kidney function decreases naturally over time. The lab order could be a preventative choice from your doctor.
  2. Related medical issues- if you have high blood pressure, diabetes, are overweight, or any combination, these factors increase the chances of developing kidney disease.
  3. Symptoms- swelling or pain in the lower half of your back near your kidneys


What kidney labs are used and what do they mean? Depending on your other health issues, the doctor may order a basic metabolic panel (BUN, creatinine, glucose, sodium, potassium, bicarbonate or CO2, chloride, and calcium) with phosphorus and albumin. Additional lab orders are anemia labs (hemoglobin and hematocrit), lipid panel (total cholesterol, LDL, and HDL), and bone parameters (Vitamin D and iPTH). Sometimes your doctor will also do a urine collection and evaluate for protein loss in the urine. GFR is not a blood test; it is a calculation. 


BUN or Blood Urea Nitrogen is the breakdown product of the protein we eat. Healthy kidneys filter BUN out of the blood and into the urine. As kidney function decreases, BUN increases.  During kidney disease, eating more protein than the kidneys can handle leads to high BUN.  


Creatinine is a breakdown product that comes from muscle. Healthy kidneys filter this in a similar way to BUN. During kidney disease, less filtering happens, and creatinine increases. People who have a lot of muscle mass may have higher creatinine levels. Creatinine is an example of why you should wait to talk to your doctor first before jumping to conclusions. Your doctor will be able to look at your labs and tell if further testing is needed to determine your kidney function.


GFR or estimated GFR- is a calculation used to determine the amount of kidney function you have. The calculation takes into account blood creatinine, sex, age, and race. GFR of 90 or above is normal; Stage 2 is considered 60-89; Stage 3a 45-59; Stage 3b 30-44; Stage 4 15-29; and Stage 5 less than 15.  Generally, electrolyte imbalances such as potassium, do not occur until later stages (4 and 5). Your medical insurance usually covers seeing a registered dietitian for chronic kidney disease. 


Sodium is a mineral found in many foods and is one of two components of Salt (sodium and chloride). In our body, sodium is essential for nerve function and fluid balance. High sodium values can be a sign of dehydration or high salt intake. Low sodium can be from overhydration, excessive loss (such as diarrhea, vomiting, diuretics), or congestive heart failure.  


Potassium is a mineral found in foods that work with nerve function and muscle contraction. In particular, potassium works to keep your heart beating regularly. Potassium’s role in muscle contraction is why it is so important to keep in a healthy range. If your potassium is low or in range, it is beneficial to eat lots of different kinds of fruits and vegetables. You do not need to restrict potassium unless it is high or your doctor has told you to avoid high potassium foods. Some medications can make potassium high; if your doctor has told you to avoid high potassium foods, make sure to know why they are making this recommendation. If you do not know, call your doctor and ask for clarification. 


Bicarbonate (CO2) helps with acid/base balance in the blood. When your blood is in balance, many proteins and enzymes work together as they should. Low or high CO2 can lead to an imbalance. Doctors will sometimes prescribe sodium bicarbonate tablets to help keep blood bicarb in range. Another way to increase blood CO2 is to eat fruits and vegetables. Fruits and veggies help produce CO2 in your blood, keeping a healthy range by using food instead of medicine. (You should not stop taking sodium bicarb until instructed to do so by your doctor)


Chloride is a mineral in food and electrolyte used to evaluate fluid and acid/base balance. It is often not evaluated alone, but instead alongside the other electrolytes.


Calcium is the main mineral in our bones. Calcium usually stays within range until very late in CKD (Stage 5 or dialysis). One of the functions of our kidneys is bone health. The kidneys regulate how much calcium and phosphorus is absorbed into our blood. It is good to get calcium naturally from food and avoid taking calcium supplements unless your doctor tells you otherwise. 



Glucose is another name for blood sugar. The ideal ranges for blood sugar are different, whether the doctor has told you to fast or not. In target fasted blood glucose is considered less than 100 mg/dL. The normal range for non-fasted blood glucose is less than 200mg/dL. Glucose does not diagnose anyone with kidney disease; however, diabetes is a risk factor for kidney disease, and very high blood glucose can change some of the other lab tests. 


Phosphorus is the 2nd most common mineral in the body after calcium. Phosphorus also usually stays in range until late CKD. As mentioned with calcium, serum phosphorus absorption is also regulated by the kidneys. Phosphorus is also a common food additive. Phosphorus that is used as an additive is absorbed easily into the body. In late-stage CKD, people who have high phosphorus are counseled to reduce phosphorus intake and may have to take a medication called a phosphorus binder with meals.  


Albumin is an indicator of protein and nutritional status. Albumin is a protein found in the blood. In some cases low albumin can  indicate malnutrition, but more often it declines because of inflammation, illness, stress and hydration status. When these situations happen, your albumin will drop even if you are eating well.During kidney disease, the kidneys are not able to filter as well. When this happens, albumin can end up in your urine. Doctors will sometimes ask for a urine collection, and they are usually looking for albumin or protein in your urine. Protein in your urine is a risk factor for kidney disease. 


Hemoglobin and hematocrit are the amount and percentage of red blood cells in your blood. As kidney disease gets worse, the kidneys are not able to make red blood cells as efficiently. Anemia’s signs and symptoms are tiredness, shortness of breath, weakness, pale skin, body aches, chest pain, dizziness, irregular heartbeat, and sleep problems. 

 Bone Parameters

Bone Parameters usually include vitamin D and PTH. People often think of vitamin D as the vitamin D from the sun. The sun and foods that have added vitamin D are the usual ways we get vitamin D. Once vitamin D is in the body, it is repackaged and becomes a new form. The last repackaging location is the kidneys. As the kidneys lose function, the active form of vitamin D decreases. Your doctor may choose to add a vitamin D supplement. PTH or parathyroid hormone is a value used to evaluate the body’s balance of calcium and phosphorus. When PTH is high, it is a sign the bone health is not in balance.  


When to worry? Kidney disease is diagnosed after multiple lab renal function tests show high values. After the first test results,  is when you can start to make changes. It does not mean you should start following a strict renal diet from one set of lab draws. What you can do is ask yourself some questions. 


  1. Did I follow my doctor’s recommendations for the test? 
  • Did you fast? If the doctor asked you to fast and you did not, this can change the results. 
  • Did you drink enough water? Hydration is key to having accurate results. If you do not drink enough water, your results can look falsely high. 
  1. Are there parts of my diet I have been encouraged to change, and I have not?
  • Have you been told to eat less salt, sugar or lose weight? Kidney health is connected to all of these values. Reducing blood pressure, keeping blood sugar in control, and maintaining/achieving a healthy weight reduce the chance of kidney disease and can help your lab values. 
  1. Do I take all my medicines as prescribed?
  • Are you taking your blood pressure or blood sugar medicine as your doctor prescribed? If the answer is no, start following your doctor’s recommendations. Medication and diet work together to control blood pressure and blood sugar. Taking medication as prescribed can reduce your risk of kidney disease by keeping your body balanced and making the kidneys work less. Diet can take you to the next level. Following diet and lifestyle changes can lead to lasting changes, reduced work of the kidneys, and sometimes less medication.  


Where to go from here? First, start by patting yourself on the back. I mean it, do it now. Right now, you are investing in your health by reading this blog. Every time you follow a doctor’s recommendation, read about your health, or make a healthy choice, you are choosing you! Giving yourself credit for these healthy choices and celebrating them is crucial. At Happy Health Nutrition we recognize how hard it can be to get the blood test and celebrate all the healthy choices you make. We aim to help YOU be empowered by your health and make the choices YOU feel are sustainable. If you are looking for consistent support and motivation or taking the frustration and confusion out of kidney health, I am here for you! Visit me at Happy Health Nutrition, Facebook, or Instagram. To a Happy Healthy you! (Now go pat yourself on the back, I mean it)