Levels of hemoglobin-F and SIDS
A recent article hit the news regarding links between hemoglobin-F and SIDS. The news refers to a 1997 study at Wichita State University. The news article reported, in part, that "Using the medical records, the researchers found that the elevated levels of HgF correlated specifically with the presence of some of the risk factors associated with SIDS". More information follows. We have received e-mail messages asking for more information. The public has been on an information roller coaster, the result of an explosion of medical reports, each heralding a "breakthrough in SIDS research." We need to help people separate myth from fact and risk factor from cause. We will post information as it becomes available to us.
Please keep the following in mind:
- When it comes to media coverage of SIDS, we often feel a sense of frustration in being confronted with misleading headlines, announcements of so-called breakthroughs and statements taken out of context.
- Please read the article, "Mass Media's" Role in SIDS Education, at <http://sids-network.org/media.htm>.
We are currently gathering more information about this specific research and will keep you updated.
(Tuesday, November 24, 1998)
Clues on Sudden Infant Death Syndrome
Holcomb B. Noble, The New Your Times
Thousands of years after medical scholars believe the Bible inaccurately reported on it, scientists have begun to find real clues to Sudden Infant Death Syndrome, a medical condition that has killed millions of apparently healthy infants with the speed and stealth of a dart that leaves no trace.
Researchers at a regional medical center in Wichita, Kan., have found persistent levels of a blood chemical called hemoglobin-F (HgF) in victims of SIDS in the weeks or months after birth -- well after those levels should have declined. British studies with a different focus have shown similar persistent levels.
Dr. Diana L. Cochran, a professor of medicine at Wichita State University, and her colleagues reported last week at a meeting of the American Public Health Association in Washington that they had found a series of links between the higher-than-normal levels of HgF and some known risk factors for the disorder.
Hemoglobin is the red blood component that attaches itself to oxygen for distribution throughout the body. It normally switches from the HgF type, which is predominant in newborns, to hemoglobin-A, which is normally dominant in adults, within the first few months of life. The HgF does not release oxygen to the tissues as readily as hemoglobin A.
Dr. Cochran's group observed 633 infants born at Via Christi Regional Medical Center in Wichita for six months last year. Using the medical records, the researchers found that the elevated levels of HgF correlated specifically with the presence of some of the risk factors associated with SIDS, including maternal urinary tract infection, placental complications, a pregnancy weight gain of 20 pounds or less and restricted growth in infants.
"It is too soon to know, until we have many more studies, whether preventive measures can be taken" as a result of the findings, Dr. Cochran said. But she said the research might eventually lead to methods of adjusting infant HgF levels.
In 1992, the American Academy of Pediatrics recommended putting infants to sleep on their backs or sides, advice that seems to be effective, though no one knows why. This practice has lowered the annual number of deaths in the United States to 2,906 in 1996, the latest year for which statistics are available, from 5,000 in 1992.
All manner of suspects have been blamed through the centuries for the sudden infant
deaths -- from milk to suffocating bedclothes to mothers who were believed to have rolled
on their babies in their sleep. The myth of the "overlaying mother" goes back at
least to I Kings, in which one mother told King Solomon that another woman had killed her
own baby: "This woman's son died in the night because she lay on it." But each
of these early suspects has been exonerated.
Comments from Medical Professionals
Date: Thu, 03 Dec 1998 15:02:44 -0500
Several studies over the past 10 years or more have addressed the question of fetal hemoglobin levels in SIDS victims. Some have shown significant elevations, some have not. The method used for measurement has been a source of some debate, and the availability of suitable controls has also been an issue.
I cannot comment on the specifics of the study summarized without seeing the actual data and knowing some information about study design and methods used. However, to the extent that their study does confirm the prior positive studies, it is just additional confirmation that some degree of prior hypoxia (subtle, ? chronic) may have been occurring. Such results are consistent with the autopsy findings of some extent of pre-existing hypoxic exposure (tissue markers for hypoxia).
The HgF elevation in SIDS victims appears to be of potential importance only to the extent that is sheds additional light on a mechanism for SIDS. Based on the data reported in the medical literature, there is no likelihood that HgF screening in young infants would be of any value in identifying infants at risk for SIDS-----there is too much individual overlap between SIDS values and control values.
Hope this is helpful.
Dr. Carl Hunt
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