If you find this theory may apply to your health. Then go to your doctor and ask for testing. Below is a list you could ask for and use as a starting point for determining if you have a vitamin deficiency that may be in part due to an absorption problem.
Realize that a vitamin deficiency is where you are not ingesting enough of a vitamin or getting enough sunlight to activate D3 in your skin.
An absorption problem is when you are getting your vitamins and enough sunlight but are not able to process it and get it to your cells for use. It is kinda like having leak in your oil line. You can keep putting oil in but until you address the ultimate problem not enough oil is going to get where it needs to and you will have damage done.
This list is only meant as a starting point to discuss with your physician & nutritionist. It would include but is not limited to the below tests. If your doctor knows of specific cell level tests to do in addition or substitution to this list you should follow their recommendations.
1) Homocysteine,Methyl MalonicAcid (B12 in the cell itself)
2.) 25 hydrox-Vitamin D (See D flowchart)
3.) Total T3 + Total T4 (2 of 3 main hormones produced by Thyroid)
4.) Cortisol (Adrenal Cortex hormone needed for blood pressure & metabolism)
5.) Androgens/ Estrogen (Estriol is good type of estrogen see B12 flowchart)
6.) Aldersterone (Adrenal Cortex hormone regulates Sodium & Potassium)
7.) Catecholamine Fractionated test (Adrenal Medulla hormones)
8.) DHEA-S (marker of adrenal androgen synthesis, if low = hypoadrenalism or adrenal fatigue)
9.) Growth Hormone (GH) + IFG-1
10.) Comprehensive Metabolic Panel w/Egfr
11.) Complete Blood Count -CBC includes Diff/Plt (This should include a Mean Corpuscular Volume: MCV. If this number is much higher than 90 it can indicate B12 deficiency. If this number is much less than 90 it can indicate an iron deficiency.)
12.) hs-CRP (tests Inflammation which reduces absorption)
13.) Iron
14.) Calcium
15.) Adiponenctin (good, should be higher if liver is healthy) 16.) Resistin (should be lower, if higher can indicate insulin resistance)
17.) Magnesium + Phosphorous
18.) Alpha Linolenic Acid
19.) Sodium and Potassium
20.) Glucose
21.) Amylase (enzyme that breaks starch down into sugar)
22.) Lipid Panel
23.) Fatty Acid Profile, Essential S (frozen) (Tests good fats ie Omega 3s)
24.) Test of how much good and bad bacteria you have in your intestines.
25.) Celiac Disease (Tests for wheat allergy. If it is positive & your eating gluten will reduce absorption)
26.) Helicobater Pylori lgg Antibody (infection in intestines)
27.) Arterial Blood Gas Draw (Determines blood pH. If it is too low or acidic it will kill good gut bacteria ie Probiotics and reduce absorption)
If you are strapped for cash or the doctors are only willing to do a few tests do the first tests in red.
Number 3.) T3+ T4 tests are most important to do if you hair is falling out & your are having a hard time losing weight.
Number 4.) Cortisol, 5.) Androgens/ Estrogen, 6.) Aldersterone 7.) Catecholamine Fractionated test and 8.) DHEA-S might be really good to ask your doctor for if your disease seems to get better or worse depending where you are in your monthly cycle.
** You may find it helpful to print off the Supporting Data page with you too.
If a deficiency is found then discuss with your doctor if he wants you to take additional oral vitamin, spray vitamin(sublingual), an injection of the vitamin or breakdown component of the vitamin (ie Methyl-B12 instead of just straight B12)
Once you start taking the vitamins your physician suggests make sure to get retested for the vitamins you were deficient in to make sure your levels have risen. If they have not you will have to try to find other work arounds.
-Good Luck to you