Patients often think when their doctors tells them they are having a full blood count that everything is checked.  This is a misunderstanding. Vitamins are not routinely checked.  A Vitamin D Deficiency can cause 

Getting sick or Infected often

Fatigue and Tiredness

Bone and Back Pain

Depression

Impaired Wound Healing

Bone Loss

Hair Loss

Muscle Pain

A Vitamin B12 Deficiency can cause

Fatigue, falling asleep in the day

Lack of Energy

Breathlessness 

Palpitations

Pins and Needles and Electric shock Feelings

Memory Problems

Migraines

Dizzy, Feeling Faint

Blurry Vision

and many others.

GPs need to check for vitamin deficiencies before they start loading patients up with pharmaceutical  drugs for numerous symptoms that are costly and have so many distressing side effects  and which could so easily be rectified with cheap vitamins.