The aim of the study is to

1. To describe the bone morphology in patients with reduced renal function and high or low parathyroid hormone (PTH) respectively.
2. To investigate if the non-invasive method 18-Fluoride Positron Emission Tomography (18F-PET) can describe the bone turnover and reflect the bone histomorphologic changes
3. To investigate if non-oxidized PTH reflects bone turnover

Patients with reduced renal function and suspected high turnover or low turnover bone disease are recruited.

A bone biopsy and a 18F-PET scan are performed and it is investigated if the 18F-PET can discriminate high turnover from low turnover bone disease

Patients with reduced renal function:

Inclusion Criteria:

-≥ 18 years

• estimated Glomerular Filtration Rate (eGFR) ≤ 20 ml/min/1,73m2
• PTH < 150 pg/ml or PTH > 300 pg/ml

Exclusion Criteria:

• ongoing malignancy
• Allergy towards tetracyclin
• Pregnancy

Control Group:

Inclusion Criteria:

-≥ 18 years

• eGFR >= 60 ml/min
• under examination for c prostata
• Prostatic Specific Antigen (PSA) total <40 µg/l

Exclusion:

• Former kidney disease
• ionized calcium or PTH outside normal range
• Known metabolic bone disease
• treatment with anticoagulants
• Disturbed thrombosis and hemostasis

Patients under investigation for prostate cancer are recruited as bone healthy controls Patients with reduced renal function and suspected high or low bone turnover are recruited for bone biopsy, blood and urin samples and 18F-PET scan