The five different stages of kidney function are best measured by glomerular filtration rate, states DaVita HealthCare Partners Inc. To calculate a person's GFR, a formula takes into account that patient's age, race, gender and serum creatinine. Stage 3 chronic kidney disease, or moderate CKD, begins at a rate of glomerular filtration equalling 45-59 mL/min, compared to greater than 90 mL/min at stage 1 and 60-89 mL/min at stage 2.
Symptoms of stage 3 chronic kidney disease that may not be present in earlier stages include fatigue, fluid retention or swelling of extremities, and sleep problems due to muscle cramps or restless legs, according to DaVita HealthCare Partners Inc. Changes in urine texture and color may also be experienced.
Some possible changes to be aware of include a foamy consistency during urination, increased or decreased frequency of urination, and dark orange, brown or red coloration, notes DaVita HealthCare. A moderate decline in kidney function can lead to a build up of waste products in the blood stream, causing a condition known as "uremia." High blood pressure, anemia (or a shortage of red blood cells) and early bone disease are also more likely to occur in a patient who has moved into stage 3 CKD.