La tétracycline, connue sous le nom commercial Sumycin, agit en bloquant la fixation de l’ARNt sur la sous-unité 30S ribosomale, interrompant l’élongation de la chaîne protéique bactérienne. Ce mécanisme confère une activité sur un spectre large, incluant bactéries Gram positives, Gram négatives, rickettsies et spirochètes. Sa biodisponibilité digestive varie selon la prise alimentaire et les interactions avec les ions divalents comme calcium et magnésium. Sa diffusion tissulaire est importante, notamment dans les voies respiratoires et génito-urinaires. L’élimination se fait par voie rénale et biliaire. Les effets indésirables incluent photosensibilisation, troubles digestifs et coloration dentaire en cas d’administration précoce. Les guides thérapeutiques mentionnent sumycin prix, en soulignant la nécessité de restreindre son utilisation afin de limiter les résistances acquises.

Hampshire.nhs.uk

Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias R
Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias • diagnosis and management of macrocytosis and macrocytic anaemia in adults • other types of anaemia (see iron deficiency anaemia and Haemolytic anaemia • use of folate supplementation for other indications • macrocytosis refers to a raised mean cell volume resulting from enlarged erythrocytes • macrocytosis can exist alone or with anaemia. Macrocytosis without anaemia is often due to causes other than vitamin B12 and • vitamin B12 or folate deficiency is the most common cause of megaloblastic anaemia (a type of macrocytosis in which DNA • pernicious anaemia is the most common cause of vitamin B12 deficiency • pernicious anaemia has an incidence of 1:10,000 in Northern Europe • prevalence of vitamin B12 or folate deficiency has been reported as approximately 5% in those between age 65-74 years and more than 10% in those age 75 years or older • of those with vitamin B12 deficiency, approximately 10% also had low folate levels Risk factors/aetiology for folate deficiency: • inadequate dietary intake, eg due to alcoholism • certain drugs, eg colestyramine, sulfasalazine, methotrexate • inflammation, eg Crohn's disease, malaria • blood disorders, eg haemolytic anaemia Risk factors/aetiology for vitamin B12 deficiency: • most common is pernicious anaemia (impaired absorption of vitamin B12 due to lack of intrinsic factor [IF]) – pernicious anaemia is often familial (30% of cases have a family history) • autoimmune disorders, eg Crohn’s disease • inadequate dietary intake, eg due to veganism Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias Quick info:This pathway has been locally developed for South West Hampshire.
Quick info:At SUHT, a macrocytosis is an MCV of > 100 fl.
• the probability of vitamin B12 or folate deficiency increases as the MCV rises, and especially if MCV >130fl • patients receiving hydroxycarbamide usually have MCV >110fl and do not need further testing • MCV 100-110fl are more likely to be related to causes other than vitamin B12 or folate deficiency Quick info:The more common causes of macrocytosis are: • the following drugs can worsen, but not cause, vitamin B12 deficiency: • drugs such as methotrexate, azathioprine and hydroxycarbamide An isolated macrocytosis also occurs with cigarette smoking.
Quick info:At SUHT, anaemia is defined as: Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias • hypogranular neutrophils/no hypersegmented neutrophils suggest myelodysplasia • hypersegmented neutrophils and macro-ovalocytes associated with vitamin B12 and folate deficiency • uniform macrocytosis, often with stomatocytes, associated with alcohol abuse • target cells associated with liver disease • polychromasia associated with haemolysis • hypogranular neutrophils/no hypersegmented neutrophils suggest myelodysplasia • hypersegmented neutrophils and macro-ovalocytes associated with vitamin B12 and folate deficiency • uniform macrocytosis, often with stomatocytes, associated with alcohol abuse • target cells associated with liver disease Quick info:Further possible investigations should be based on blood film report and presence/absence of anaemia.
In the absence of anaemia, or changes on the blood film consistent with vitamin B12 or folate deficiency, then consider the followinginvestigations initially: • if taking methotrexate, azathioprine or hydroxycarbamide, no further investigations required in the absence of anaemia • serum vitamin B12 and serum folate assays • especially if malabsorption, severe oropharyngeal ulceration, neuropsychiatric abnormalities such as paraesthesia, ataxia, Quick info:Further possible investigations should be guided by the blood film, but may include: • reticulocyte count (raised in haemolysis or active bleeding) • serum vitamin B12 and serum folate assays • especially if malabsorption, severe oropharyngeal ulceration, neuropsychiatric abnormalities such as paraesthesia, ataxia, Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias Quick info:Biochemical hypothyroidism is characterised by: • thyroid stimulating hormone (TSH) levels greater than 10 mU/L with free thyroxine (FT4) levels low or normal; or • TSH above normal but less than 10 mU/L with normal FT4 in presence of unexplained symptoms consistent with • serum vitamin B 12 less than 160ng/L indicates deficiency • if vitamin B12 is low normal (160-180ng/L) then deficiency cannot be excluded, and repeat measurement 3 months later If there is co-existent folate and vitamin B12 deficiency, vitamin B 12 should be replaced before folate. Administration of folate inB12 deficient patients can precipitate acute combined degeneration of the cord.
• green vegetables and liver contain folate • look for low calcium (reduced vitamin D absorption) and low iron • coeliac disease (ferritin and tissue transglutaminase) • chronic inflammation (consider vasculitis) Quick info:If the above investigations are normal, check: • plasma protein electrophoresis looking for a paraprotein If no abnormality is identified, then myelodysplasia is a possibility. Either discuss with a haematologist or refer to the generalhaematology clinic if the patient has a symptomatic anaemia.
Local administrative info:
Classification of anaemias
SUHT consultants:
Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias • Dr Andrew Duncombe: Tuesday afternoons • pernicious anaemia (impaired absorption of vitamin B12 due to lack of intrinsic factor [IF]) is the most common cause – pernicious anaemia is often familial (30% of cases have a family history) • other (rare) causes or contributing factors include: • autoimmune disorders, eg Crohn’s disease • Medications that interfere with gastric acid production and can cause reduced absorption of B12 from ingested protein in food • inadequate dietary intake, eg due to veganism Check serum anti-intrinsic factor antibody: • highly specific for pernicious anaemia, but low sensitivity (50%) • if anti-intrinsic factor antibody is present, pernicious anaemia is very likely, but its absence does not rule out pernicious anaemia • sensitivity of anti-parietal cell antibody for pernicious anaemia is more than 90% – however, specificity is only 50% • in the absence of anti-parietal cell antibody it is unlikely that the person has pernicious anaemia • initial dose of levothyroxine usually 50-100micrograms daily, depending on body weight • adjust dosage by 25-50microgram increments • initial dose 25 micrograms daily if >50 years (especially those with ischaemic heart disease) and change dose by smaller • measure serum thyroid stimulating hormone (TSH) concentration after 6 weeks and titrate dose if needed • correct dose is that which restores the euthyroid state and relieves symptoms • dose of thyroxine aims to achieve TSH within lower half of the reference range Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias Give folic acid 5mg once daily for 4 months: • ensure there is no co-existent vitamin B12 deficiency - in such individuals, vitamin B 12 should be replaced before folate • administration of folate in B12 deficient patients can precipitate acute combined degeneration of the cord Quick info:Review after 4 months, with full blood count.
If cause of folate deficiency has been addressed, stop treatment. Otherwise, consider long term treatment Quick info:Consider seeking specialist advice in pregnancy or if there are neurological symptoms.
• intramuscular (IM) injections of hydroxocobalamin on alternate days for 2 weeks Long-term treatment where the underlying cause is not dietary: • IM injections of hydroxocobalamin every 3 months for life Long-term treatment where the underlying cause is dietary: • oral cyanocobalamin tablets daily between meals (available as a food supplement, and only prescribable on FP10 under special circumstances with 'SLS' endorsement required- see BNF); or • twice-yearly hydroxocobalamin injection (may be preferable in the elderly who are more likely to have malabsorption) • in vegans, this treatment may need to be life-long • in non-vegans treatment can be stopped once vitamin B12 levels have been corrected and diet has improved • advise consumption of foods rich in vitamin B12, eg: • foods fortified with vitamin B12 – some soy products, and some breakfast cereals and breads Quick info:Full blood count (FBC) and reticulocyte count should be performed after 10 days to check response to treatment: • there should be a rise in the haemoglobin level and an increase in the reticulocyte count to above normal range • if there is no improvement, check serum folate level (if this has not already been done) FBC after 8 weeks to confirm normal blood count Further monitoring is generally considered unnecessary – exceptions to this are: • suspected lack of compliance with treatment Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.
Macrocytosis and macrocytic anaemiasMedicine > Haematology and haemostasis > Macrocytosis and macrocytic anaemias Published: 19-May-2011, by Southampton Area Published: 19-May-2011 Valid until: 19-May-2012 Printed on: 01-Aug-2011 Map of Medicine LtdThis care map was published by Southampton Area. A printed version of this document is not controlled so may not be up-to-date with thelatest clinical information.

Source: http://www.hampshire.nhs.uk/primary-care/mapofmedicine/Macrocytosis%20and%20macrocytic%20anaemias-1.pdf