Does Correction of 25 OH-VITAmin D With Cholecalciferol Supplementation Increase Muscle Strength in hemoDIALysis Patients?

Muscle strength decreases as renal failure progresses. Low muscle strength affects more than 50% of hemodialysis patients and leads to daily life activities impairment. In the general population, numerous studies have linked low 25OH-vitamin D (25OHD) concentrations to the loss of the muscle strength and low physical performances. Data on native vitamin D and muscle function are scarce in the chronic renal failure (CKD) population, but low 25OHD levels have been associated with poor muscle strength. In this protocol of an ongoing study named VITADIAL testing if cholecalciferol supplementation in hemodialysis patients with low 25OHD improve their muscle strength.

Prospective open randomized French multicenter study. All patients will have 25OHD levels ≤50nmol/L at randomization. One group will receive 100 000 UI cholecalciferol once a month during 6 months, the other group will receive no treatment during 6 months.

In order to randomize patients with 25OHD ≤50nmol/L, supplemented patients will undergo a 3 months wash-out period renewable 3 times (maximum of 12 months wash-out) until 25OHD reaches a level≤50nmol/L.

The main objective of this study is to analyze if a 6 months period of oral cholecalciferol (i.e. native vitamin D) supplementation improves muscle strength of hemodialysis patients with low 25OHD vitamin D levels. Muscle strength will be assessed at 0, 3 and 6 months, by handgrip strength measured with a quantitative dynamometer.

Secondary objectives are 1) to analyze 25OHD plasma levels after vitamin D wash-out and/or supplementation, as well as factors associated with 25OHD lowering speed during wash-out and 2) to analyze if this supplementation improves patient's autonomy, reduces frailty risk and improves quality of life.

Eligibility Criteria:
* Inclusion Criteria:

  * under hemodialysis for more than 3 months
  * aged over 18 years-old
  * gave their consent
* Non-inclusion criteria :

  * non fluent French speaker
  * incapacity to provide consent or to answer questionnaires
  * pregnancy or breast feeding
  * cognitive impairment
  * bedridden or life expectancy \<1 year
  * active cancer
  * uncontrolled hyperparathyroidism as defined by the K-DIGO (iPTH\>9x normal laboratory maximal value), cinacalcet treatment or hypocalcemia \<2.0 mmol/L or hypercalcemia \>2.7mmol/L
  * past osteoporosis fracture
  * treatment with active vitamin D
  * unable to perform handgrip measurement
  * 25OHD\>50nmol/L without vitamin D treatment
  * cholecalciferol intolerance or allergy
* Exclusion Criteria:

  * 25OHD\>50nmol/L after 12 months wash-out
  * hypercalcemia \>2.7mmol/L
  * hyperparathyroidism (iPTH\>9x normal laboratory maximal value) during wash-out or after randomization if patient is in the no treatment group
  * hypoparathyroidism (iPTH\<3x normal laboratory lower value) in a patient receiving cholecalciferol
  * cholecalciferol intolerance or allergy
  * death, renal transplantation
  * pregnancy
  * consent withdrawal
  * renal recuperation allowing hemodialysis to stop
  * unability to perform handgrip