• existence of a circadian rhythm of cortisol and IGF-1 [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
• Relationship between temperature and melatonin. Relationship between blood pressure and erythropoietin [ Time Frame: 24 hours ] [ Designated as safety issue: No ]

Rationale: Investigation of the circadian rhythm of erythropoietin and melatonin in patients with various degrees of renal insufficiency

Objectives:

Primary objective: Is there a circadian rhythm of epo and melatonin in patients with various degrees of renal insufficiency?

Primary Objective: Is there a circadian rhythm of epo and melatonin in patients with various degrees of renal insufficiency compared to patients with a normal renal function?

Secondary Objective: Is there a circadian rhythm of cortisol and IGF in patients with various degrees of renal insufficiency?

Secondary Objective: Is there a circadian rhythm of cortisol and IGF in patients with various degrees of renal insufficiency compared to patients with a normal renal function?

Study design: Comparative study in 4 groups with various degrees of renal insufficiency, duration for each patient 24 hrs. Total duration of study 12 months, patients admitted to the hospital (on nursing ward)

Study population: Patients with various degrees of renal insufficiency

Main study parameters/endpoints: Analysis of the existence of a circadian rhythm in patients with a normal renal function and in patients with variable degrees of renal insufficiency

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Better knowledge of the circadian rhythm in renal insufficiency. This could lead to a more efficient administration of erythropoietin and melatonin in the future.

Extent of burden is 1 venapunction for placement of infusion needle, the withdrawal of 11 times 5 ml blood in 24 hrs, continuous measurement of body temperature via capsule, 24-hour continuous ambulant blood pressure monitoring.

• MDRD 10-30
• MDRD 30-60
• MDRD 60-80
• MDRD > 80

Inclusion criteria:

• Patient with various degrees of renal insufficiency, stable creatinin clearance: minimum 10 ml/min (measured with MDRD), admitted to our hospital
• Informed Consent
• Man/Women between 18 and 85 years
• Understanding and knowledge of the dutch language

Exclusion criteria:

• Instable angina pectoris, heart failure NYHA class IV
• Therapy with erythropoetin, melatonin and hypnotics
• Acute renal failure or rapidly progressive glomerulonephritis
• Bleeding or hemolysis as a cause of anemia
• Deficiency of iron, folate and/or vitamin B12
• Presence of chronic inflammatory disease or clinically significant infection
• Hemoglobinopathies
• Alcohol and/or drug abuse
• Enrolment in another study
• Any kind of disorder that compromises the ability of the subject to give written informed consent and/or to comply with study procedures

• Stichting Bijstand, Meander Medical Center
• Hoffmann-La Roche