Imethemoglobinemia

I-Methemoglobinemia (MetHb) sisifo segazi apho kuveliswa inani elingaqhelekanga le-methemoglobin. IHemoglobin yiprotein ekwiiseli ezibomvu zegazi (RBCs) ezithwala kwaye zisasaze ioksijini emzimbeni. I-Methemoglobin luhlobo lwehemoglobin.

Nge-methemoglobinemia, i-hemoglobin inokuthwala ioksijini, kodwa ayikwazi ukuyikhulula ngokufanelekileyo kwizicubu zomzimba.

Imeko yeMetHb inokuba:

• Ukudlula kwiintsapho (ezelwe njengelifa okanye ukuzalwa)
• Kubangelwa kukuchaphazeleka kumayeza athile, iikhemikhali, okanye ukutya (kufunyenwe)

Zimbini iindlela zokufumana ilifa leMetHb. Ifom yokuqala idluliselwa ngabazali bobabini. Ngokuqhelekileyo abazali abanayo imeko ngokwabo. Baphethe imfuza ebangela imeko. Kwenzeka xa kukho ingxaki nge-enzyme ebizwa ngokuba yi-cytochrome b5 reductase.

Zimbini iintlobo zeMetHb ezuzwe njengelifa:

• Uhlobo lwe-1 (ekwabizwa ngokuba yi-erythrocyte reductase defence) lwenzeka xa ii-RBCs zingenayo i-enzyme.
• Uhlobo lwe-2 (ekwabizwa ngokuba kukusilela ngokubanzi kokunciphisa) lwenzeka xa i-enzyme ingasebenzi emzimbeni.

Ifom yesibini ye-MetHb eyabelwe ilifa ibizwa ngokuba yi-hemoglobin M isifo. Kubangelwa ziziphene kwiproteni yehemoglobin uqobo. Mnye kuphela umzali ekufuneka edlulise uhlobo olungaqhelekanga lomntwana ukuba asizuze njengelifa esi sifo.

Ukufunyanwa kweMetHb kuqheleke ngakumbi kuneefom ezizuzwe njengelifa. Iyenzeka kwabanye abantu emva kokuba bevezwe kwiikhemikhali ezithile kunye namayeza, kubandakanya:

• Iintlungu ezifana ne-benzocaine
• Nitrobenzene
• Ezinye i-antibiotics (kuquka i-dapsone kunye ne-chloroquine)
• IiNitrites (ezisetyenziswa njengezongezo ukunqanda inyama ukuba ingonakali)

Iimpawu zohlobo 1 MetHb zibandakanya:

• Umbala oluhlaza okwesibhakabhaka

Iimpawu zohlobo 2 MetHb zibandakanya:

• Ukulibaziseka kophuhliso
• Ukungaphumeleli
• Ukukhubazeka kwengqondo
• Ukuxhuzula

Iimpawu zesifo se-hemoglobin M zibandakanya:

• Umbala oluhlaza okwesibhakabhaka

Iimpawu zokufunyanwa kweMetHb zibandakanya:

• Umbala oluhlaza okwesibhakabhaka
• Intloko ebuhlungu
• Ubuncwane
• Isimo sengqondo esitshintshileyo
• Ukudinwa
• Ukuqhawukelwa ngumphefumlo
• Ukungabikho kwamandla

Usana olunale meko luya kuba nombala wolusu oluhlaza okwesibhakabhaka (cyanosis) ekuzalweni okanye kungekudala emva koko. Umboneleli wezempilo uya kwenza uvavanyo lwegazi ukufumanisa imeko. Uvavanyo lunokubandakanya:

• Ukujonga inqanaba leoksijini egazini (pulse oximetry)
• Uvavanyo lwegazi ukujonga amanqanaba egesi egazini (uhlalutyo lwegesi yegazi)

Abantu abanesifo sehemoglobin M abanazo iimpawu. Ke, abanokufuna unyango.

Iyeza elibizwa ngokuba yi-methylene blue lisetyenziselwa ukunyanga iMetHb ebukhali. I-Methylene eluhlaza okwesibhakabhaka inokungakhuselekanga kubantu abanesifo segazi esibizwa ngokuba yi-G6PD. Akufunekanga bathathe eli yeza. Ukuba wena okanye umntwana wakho unokusilela kwe-G6PD, soloko uxelela umboneleli wakho ngaphambi kokufumana unyango.

I-Ascorbic acid inokusetyenziselwa ukunciphisa inqanaba lemethemoglobin.

Olunye unyango lubandakanya unyango lwehyperbaric oksijini, utofelo-gazi lwegazi kunye notshintshiselwano ngegazi.

Kwiimeko ezininzi zeMetHb efumanekayo, akukho nyango luyafuneka. Kodwa kuya kufuneka uliphephe iyeza okanye imichiza ebangele ingxaki. Iimeko ezinzima zingadinga ukutofelwa igazi.

Abantu abane-1 MetHb kunye nesifo se-hemoglobin M bahlala besenza kakuhle. Uhlobo lwe-2 MetHb lubaluleke kakhulu. Ihlala ibangela ukufa kwiminyaka embalwa yokuqala yobomi.

Abantu abane-MetHb efunyenweyo bahlala benza kakuhle xa iyeza, ukutya, okanye imichiza ebangele ingxaki ichongiwe kwaye ithintelwe.

Iingxaki zeMetHb zibandakanya:

• Umothuko
• Ukuxhuzula
• Ukufa

Fowunela umnikezeli wakho ukuba:

• Unembali yosapho yeMetHb
• Phuhlisa iimpawu zokuphazamiseka

Tsalela umnikezeli wakho okanye iinkonzo zikaxakeka (911) ngoko nangoko ukuba uphefumla kakhulu.

Ukucebisa ngemfuza kuyacetyiswa kwizibini ezinembali yosapho yeMetHb kwaye zijonga ukuba nabantwana.

Iintsana kwiinyanga ezi-6 okanye ngaphantsi kunokwenzeka ukuba ziphuhlise i-methemoglobinemia. Ke ngoko, ukutya okwenziwe ngabantwana okusulungekileyo okwenziwe kwimifuno enamanqanaba aphezulu eitrate, ezinje ngeekherothi, beetroots, okanye isipinatshi kufuneka kuthintelwe.

Isifo seHemoglobin M; Ukusilela kwe-Erythrocyte reductase; Ukusilela kokunciphisa ngokubanzi; MetHb

• Iiseli zegazi

I-Benz EJ, i-Ebert BL. Ukwahluka kweHemoglobin okunxulunyaniswa ne-hemolytic anemia, ukutshintsha kwe-oksijini, kunye ne-methemoglobinemias. Ku: Hoffman R, Benz EJ, Silberstein LE, ii-eds. I-Hematology: Imigaqo esisiseko kunye nokuziqhelanisa. Umhla wesi-7. IPhiladelphia, PA: Elsevier; I-2018: isahluko 43.

U-Letterio J, Pateva I, Petrosiute A, Ahuja S. Hematologic kunye neengxaki ze-oncologic kwimveku engekazalwa. Ku: UMartin RJ, uFanaroff AA, uWalsh MC, ii-eds. UFanaroff kunye noMartin's Neonatal-Perinatal Medicine. Ngomhla we-11. IPhiladelphia, PA: Elsevier; 2020: isahl. 79.

Kuthetha i-RT. Indlela eya kwii-anemias. Ku: IGoldman L, iSchafer AI, ii-eds. Amayeza eGoldman-Cecil. Ngomhla wama-26. IPhiladelphia, PA: Elsevier; 2020: isahluko 149.