Type of test Blood; urine

Normal findings

 Vitamin B12 : 160-950 pg/mL or 118-701 pmol/L (SI units)

MMA: < 3.6 μmol/mmol creatinine

 Test explanation and related physiology

 Vitamin B12 is necessary for conversion of the inactive form of folate to the active form. This function is most notable in the formation and function of RBCs. Vitamin B12 deficiency, like folic acid deficiency, causes anemia. The RBCs formed in light of these deficiencies consist of large megaloblastic RBCs. These RBCs cannot conform to the size of small capillaries. Instead, they fracture and hemolyze. The shortened life span ultimately leads to anemia.

In the stomach, gastric acid detaches vitamin B12 from its binding proteins. Intrinsic factor (IF), which is necessary for vita min B12 absorption in the terminal ileum, is made in the stomach mucosa. Without IF, vitamin B12 cannot be absorbed. Deficiency of IF is the most common cause of vitamin B12 deficiency (pernicious anemia). The next most common cause of vitamin B12 deficiency is lack of gastric acid to separate the ingested vitamin B12 from its binding proteins. This is common in patients who have had gastric surgery. A third cause of vitamin B12 deficiency is malabsorption caused by diseases of the small terminal ileum. Vitamin B12 deficiency is common in poorly nourished elderly people and in vegetarians.

Serum B12 is a measurement of recent B12 ingestion. More prolonged B12 deficiency is better and more easily measured by urinary methylmalonic acid (MMA) measurement. Elevated serum MMA levels and urinary excretion of MMA are direct measures of tissue vitamin B12 activity. The active form of B12 is essential in the intracellular conversion of L-methylmalonyl coenzyme A (MMA CoA) to succinyl CoA. Without B12 , MMA CoA metabolism is diverted to make large quantities of MMA. MMA is then excreted by the kidneys. MMA testing is the most sensitive test for B12 deficiency.

Procedure and patient care

• See inside front cover for Routine Blood Testing.

• Fasting: verify with laboratory

• Blood tube commonly used: red

* Instruct the patient not to consume alcoholic beverages before the test. Check the time period with the physician or laboratory.

• Draw the specimen before starting vitamin B12 therapy.

 Abnormal findings

 Increased levels

- Leukemia

- Polycythemia vera

- Severe liver dysfunction

- Myeloproliferative disease

Decreased levels

- Pernicious anemia

- Malabsorption syndromes

- Inflammatory bowel disease

- Intestinal worm infestation

- Atrophic gastritis

- Zollinger-Ellison syndrome

- Large proximal gastrectomy

- Resection of terminal ileum

- Achlorhydria

- Pregnancy

- Vitamin C deficiency

- Folic acid deficiency

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الشؤون الفكرية يصدر كتاب (دروس تمهيدية في الفقه – العبادات)

قسم الشؤون الطبية يشرع بتقديم لقاح الانفلونزا للمنتسبين

المجمع العلمي يختتم مسابقة العميد لحفظ القرآن الكريم في بغداد

لجنة البرامج المركزية تختتم فعاليات البرنامج المركزي الأسبوعي لمنتسبي العتبة العباسية المقدسة

المزيد

الآخبار الصحية

عناصر منزلية قد تؤثر على الخصوبة وفرص الحمل

شكل الدماغ قد يتنبأ بخطر الخرف قبل سنوات

طريقة صينية بسيطة للوقاية من السكري

هل تساعد المانغو في الوقاية من السكري؟

المزيد

الآخبار التكنلوجية

رقم غامض ولا إنترنت.. متوجون بنوبل للطب لم يعلموا بفوزهم

"سيري" تحت المجهر.. تحقيق فرنسي جديد ضد شركة "آبل"

أميركيان وياباني يفوزون بجائزة نوبل للطب

تحول غير مسبوق.. إنستغرام تمنح مفاتيحها للمستخدمين

المزيد

مواضيع ذات صلة

white blood cell scan (WBC scan, Inflammatory scan)

white blood cell count and differential count (WBC and differential, Leukocyte count)

vitamin D (25-hydroxy vitamin D2 and D3 ; 1,25-dihydroxyvitamin D [1,25(OH)2 D])

Basal Hormone Measurements of Testis

virus testing

viral cultures

Laboratory Investigations of Pheochromocytoma and Paraganglioma

varicella virus testing (Antibody testing for Varicella zoster virus, Varicella zoster virus [VZV], Herpes virus-3)

uroporphyrinogen-1-synthase

urine culture and sensitivity (C&S)

uric acid, blood, and urine

urea breath test (UBT, Helicobacter pylori breath test)