Study Participants

Study Participants

Research studies like HiLo cannot be completed without participants who volunteer to be involved. Study participants in HiLo will contribute health information and other valuable data to help doctors know how best to manage blood phosphate levels for future kidney patients receiving dialysis.


What is the best level of phosphate for people with kidney failure on dialysis?

“There is a lot that we do not know about how to provide the best care to patients with chronic kidney disease who are receiving dialysis. Researchers are better able to answer important questions, like the best treatment target for serum phosphorus in dialysis, when they collaborate with patients.”

Susan Mendley, MD
Program Director, NIH/NIDDK


Participating dialysis units and patients from those facilities who enroll in HiLo will be randomly assigned to either a high blood phosphate goal or a low blood phosphate goal. There will be no extra tests, dialysis sessions, blood work or additional responsibilities for you. If you choose to participate in HiLo, you will:

  • Continue to receive the same medical care you receive now.
  • If you are randomized to the high group, you will aim to keep your blood phosphate level at a higher level, above the current goal. You may be able to reduce the number of phosphate binders you take and relax your dietary restrictions.
  • Continue to work with your dietitian and nephrologist to reach your phosphate goal.

Even though this is a clinical research study – being part of it will feel no different from your standard medical care. This type of research is called pragmatic. It is a relatively new approach to clinical trials that helps us learn how to best care for patients in the real world situations.

Why is Research on Blood Phosphate Levels Needed?

The best phosphate goal for people with kidney failure has never been studied in a formal research study. For years, doctors and dietitians have managed phosphate levels based on expert opinion. We have thought it is a good idea to lower serum phosphate, but we never proved if a low phosphate level is helping patients live longer and avoid hospitalization.

Because getting phosphate levels down to the current standard goal can be challenging for patients and carry certain risks, doctors, dietitians, and researchers think it is time to finally do a clinical research study to determine the best blood phosphate level for patients being treated with hemodialysis. This is what the HiLo study intends to do.


Phosphate in Food

  • Present in high quantities in meats, whole grain breads, processed foods, cola beverages, cheese, dried beans, dried peas, liver, peanut butter, dairy products, and chocolate.
  • A component of many commonly used additives used by the food industry to preserve and extend the shelf life of food.
  • Learn more about hidden phosphate in foods.



Phosphorus, Phosphate and Kidney Disease

Phosphorus is a mineral found in your bones. Along with calcium, phosphorus is important for bone health and many other processes in the body. The kidneys are responsible for controlling blood phosphate levels. However, when your kidneys are not working as well as they should, phosphate levels rise. Too much blood phosphate is called hyperphosphatemia.

Too much phosphate in your blood can pull calcium out of your bones, making them weak. High phosphate and calcium levels can lead to calcium deposits in your blood vessels, lungs, eyes, and heart. Over time, this can lead to increased risk of heart attack, stroke or death.

Managing phosphate levels is important, but doctors are not sure what is the best level of phosphate for people with kidney failure on dialysis. HiLo will help doctors understand how to manage phosphate levels for patients on dialysis.