The most important blood tests (II)

CRP: Why is C-reactive protein measured?

C-reactive protein (CRP) is synthesized and released in the liver in response to inflammation or tumours. CRP belongs to the „acute phase proteins“ and is a non-specific, inflammation parameter. It is measured when an inflammation is suspected . In the case of inflammation it increases ; this can be caused by a bacterial infection, but not by a viral infection. CRP levels are also elevated during chronic inflammations .

What does a low/high CRP value mean?

Low CRP values have no clinical significance. High CRP values can indicate an acute bacterial infection, e.g. pneumonia, meningitis, chronic inflammations (such as, Crohn‘s disease or rheumatic diseases). But the value can also be elevated after surgeries, in the case of a heart attack or certain tumours. Vitamin B12: When is a vitamin B12 analysis indicated?

Vitamin B12 (a.k.a. Cobalamin) is a water-soluble vitamin that humans mainly gain from animal food products like kidney, liver, meat, fish, eggs or milk. Among other functions, cobalamin is important for cell division, for nervous system functioning, and plays a major role in blood formation.

Older people often have a vitamin B12 deficiency. Often, it is a consequence of insufficient gastric juice production. There are also a number of drugs that inhibit intestinal absorption. Why is the analysis of vitamin B12 important?

Even a slight impairment of vitamin B12 levels is associated with neuropsychiatric or neurological symptoms (concentration disorders, depressed mood, ataxia). Furthermore, researchers suspect that an insufficient vitamin B12 supply negatively influences the development or course of dementia diseases such as Alzheimer‘s disease. This is especially true if vitamin B12 deficits are accompanied by a low folic acid level. In particular, the neurological symptoms are only reversible in the earliest stages via suplementation.

What does transcobalamin and haptocorrin in combination with vitamin B12 mean?

Vitamin B12 in plasma is coupled to different transport proteins: when combined with haptocorrin it forms biologically inactive holo-hapto-corrin, and combined with transcobalamin it forms biologically active holoTC. The holo-haptocorrin-vitamin B12 complex represents up to 80–90 % of the total plasma vitamin B12, whereas the holoTC represents just some 10–20 %. HoloTC is considered to be the biologically active vitamin B12, because it can be absorbed into the cell via specific transcobalamin receptors.

Low holoTC is a strong initial indicator of vitamin B12 depletion. Any decrease in total vitamin B12 is an serious marker that the decline is already advanced, especially because other laboratory diagnostic signs such as macrocytic anaemia may be absent and there are no specific laboratory analyses for the neurological/neuropsychiatric changes that have already occurred!

What does a low/high vitamin B12 level mean?

Low vitamin B12 levels can indicate vitamin B12-related anaemia (pernicious anaemia), damage to the spinal cord (funicular myelo-sis), malnutrition , e.g. after stomach surgery , Crohn‘s disease or infection by the fish tapeworm. Overly high vitamin B12 levels are very seldom. Vitamin D: Why is vitamin D measured?

Vitamin D is a group of lipid soluble vitamins that are important for calcium metabolism and bone formation. Among them vitamin D3 is the most physiologically relevant Vitamin D. Usually, our skin produces sufficient vitamin D3 (cholecalciferol, about 80–90 %) when enough UV-B rays from sunlight reach the skin. Vitamin D supply, therefore, depends strongly on latitude , season, clothing and personal pigmentation. In contrast to other vitamins, humans only absorb a small part of vitamin D through food – for example, through fatty sea fish. We only consume up to 10 % of the required amount of vitamin D with our food. Fish like herring, salmon and mackerel are especially rich in vitamin D. The liver converts vitamin D into its storage form, 25-OH vitamin D.

How is the vitamin D metabolised?

Ingested or UV-dependent synthesized vitamin D binds (in the bloodstream) to a binding protein and is converted (in the liver) into 25(OH)-vitamin D. This is a storage form: it has a low biological activity but is present with the highest concentration in the blood circulation. Therefore, the determination of 25(OH)-vitamin D is the best way to determine the vitamin D supply. 25(OH)-vitamin D is subsequently metabolised to 1,25(OH)2-vitamin D (in the kidneys), the most biologically active form of vitamin D. However, 1,25(OH)2-vitamin D analyses do not allow prognoses about the long-term supply of vitamin D.

What does a low/high level mean?

A pronounced vitamin D deficiency leads to rickets in children and to osteomalacia in adults. Hypervitaminosis D occurrs rarely. An associated syndrome may be hypercalcemia, which can cause weakness, frequent urination, nausea and vomiting. What are the functions of vitamin D?

Vitamin D regulates calcium levels in the blood and is important for bone formation. Vitamin D also plays an important role in various organ systems and tissues. For example, it plays a role in immune modulation, in apoptotic processes, in the differentiation of cells and cell systems, and also in the inhibition of cell proliferation.

EXERCISE: 1. Vitamin B12 in plasma is coupled to haptocorrin and to transcobalamin.

a) True b) False

2. Which food contains Vitamin D?

a) Salmon b) Eggs c) Mackerel d) Milk e) Liver

3. The best way to determine the vitamin D supply is to determine 25(OH)-vitamin D.

a) True b) False

4. CRP is increased in the case of inflammation caused by bacterial infection and viral infection.

a) True b) False

You’ll find the answer on the next page

BIBLIOGRAPHY 1. http://dict.leo.org. 2. www.dict.cc. 3. Dormann A, Isermann B, Heer Ch: Laborwerte 7th edition, Elsevier 2018. 4. www.webster-dictionary.org.

CARMEN LOBITZ Carmen Lobitz ist freie Trainerin, Lehrerin und MTA. Sie gründete 1998 in Berlin lobitz seminare, die unter anderem Englischseminare für Health Professionals anbieten. Kontakt: mail@lobitz-seminare.de www.lobitz-seminare.de

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Lösung für Exercise:

1. A

2. A + C

3. A

4. B

The most important blood tests (II)

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