Type of test Blood

 Normal findings

0.06-0.24 g/dL or 9.3-37.2 μmol/L (SI units)

0.4%-1.5% of total hemoglobin

 Possible critical values

 > 40% of total hemoglobin

Test explanation and related physiology

 Methemoglobin is formed during the production of normal adult hemoglobin. If oxygenation of the iron component in the protohemoglobin occurs without subsequent reduction of the heme iron back to its Fe+2 form as exists in normal hemoglobin, excess methemoglobin accumulates. The oxidized iron form in methemoglobin is unable to combine with oxygen to carry the oxygen to the peripheral tissues. Therefore the oxyhemoglobin dissociation curve is shifted to the left, resulting in cyanosis and hypoxia.

Methemoglobinemia can be congenital or acquired. Hemoglobin M disease is a genetic defect that results in a group of abnormal hemoglobins that are methemoglobins. Another genetic mutation can cause a deficiency in reduced nicotinamide adenine dinucleotide (NADH) methemoglobin reductase enzyme, which is required to deoxygenate methemoglobin to normal adult hemoglobin. These forms of methemoglobinemia occur in infants, are usually severe, are not amenable to treatment, and are often fatal.

Acquired methemoglobinemia is a result of ingestion of nitrates (e.g., from well water) or such drugs as phenacetin, sulfonamides, isoniazid, local anesthetics, and some antibiotics. This form of the disease commonly occurs in older individuals and results in an acute crisis that is treated effectively with ascorbic acid or methylene blue. Methylene blue, however, is contraindicated in glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Interfering factors

• Tobacco use and carbon monoxide poisoning are associated with increased methemoglobin levels.

* Drugs that may cause increased levels include some antibiotics, isoniazid, local anesthetics, and sulfonamides.

Procedure and patient care

• See inside front cover for Routine Blood Testing.

• Fasting: no

• Blood tube commonly used: green

• Methemoglobin is very unstable. Place the specimen in an ice slush immediately after collection.

• Be prepared to provide oxygen support and close monitoring in the event the patient becomes increasingly hypoxic.

 Abnormal findings

 Methemoglobinemia (hereditary or acquired)

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الشؤون الفكرية يختتم المرحلة الثالثة من مشروع استعادة مكتبة جامعة الموصل

جامعة الكفيل تنظّم دورة حول نظام (كوها) العالمي لإدارة المكتبات الجامعية في النجف

مجموعة مشاتل الكفيل: إضافة نحو 70 نوعًا جديدًا من المغروسات تتناسب مع الظروف المناخية المحلية

المجمَع العلمي يطلق الدورة التطويرية الخامسة لمعلمي التربية الإسلامية ومدرسيها في النجف الأشرف

المزيد

الآخبار الصحية

اختراق علمي.. دواء يؤخر ظهور السكري من النوع الأول لسنوات

هذا ما يحدث لجسمك إن أهملت نظافة فراشك

لماذا تعتبر النساء أكثر عرضة للإصابة بألزهايمر من الرجال؟

لماذا يحذر الخبراء من الإفراط في تناول الفراولة؟

المزيد

الآخبار التكنلوجية

السيارات الكهربائية أنظف بنسبة 73% من سيارات الوقود

سيارة لوسِد الكهربائية تدخل "غينيس" بأطول مدى في العالم

نظرية جديدة تنسف كل ما نعرفه عن تشكل أول قارة في الأرض

منذ 37 ألف عام.. دراسة تكشف "أقدم أمراض" أصابت البشر

المزيد

مواضيع ذات صلة

microalbumin (MA)

methylated septin 9 DNA (mSEPT9, ColoVantage)

metanephrine, plasma free (Fractionated metanephrines)

measles rubeola antibody

maternal screen testing (Maternal triple screen, Maternal quadruple screen)

C-Reactive Protein Rapid Latex Agglutination Test

Hyporegenerative Macrocytic Anemias/ Megaloblastic Anemias

Unstable Hemoglobins

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency

Hereditary Spherocytosis

Magnesium

lyme disease test