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January 29, 2015

Color of Snot (Infographic)

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January 27, 2015

Large Thyroid Nodules Have Higher Risk of Cancer Even if Needle Biopsyis Normal

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A recent 2015 study revealed that large thyroid nodules (over 3cm) have a higher risk of cancer and that needle biopsies are not very accurate in diagnosing cancer in such large nodules. This is hardly the first study to demonstrate this.

In a 2009 study, surgeons at the University of Wisconsin found that fine needle aspiration biopsy (FNAB) in 26 of 52 FNAB reported as benign (50.0%) turned out to be either neoplastic (22) or malignant (4) on final pathologic analysis after thyroidectomy. Among patients with nondiagnostic FNAB results, the risk of malignant neoplasms was 27.3%. Even for smaller thyroid masses, FNAB is still not 100% accurate with a falsely negative rate of around 10%.

In the 2015 study (meta-analysis based on 15 other studies), a total of 13,180 patients were analyzed who underwent thyroid nodule biopsies. What they found was that the best-reported studies suggests sensitivity, false-negative rates, and frequency of true negatives among benign needle biopsy results are worse in large nodules (over 3cm).

These findings all suggest that thyroidectomy may be the best course to take regardless of needle biopsy results (if performed) in large thyroid nodules.

So what does this mean for a patient with a thyroid mass?

1) The ONLY way to know 100% whether a patient has thyroid cancer or not is to remove the thyroid.
2) IF the needle biopsy shows thyroid cancer, total thyroidectomy is recommended.
3) IF the needle biopsy does not show thyroid cancer, thyroid cancer can STILL be there; it's just that the needle biopsy was wrong; and the risk of a wrong results is higher the larger the nodule, especially if over 3cm in size. Thyroid lobectomy should still be considered.

Of course, one needs to talk with your local surgeon on what the next step is.

Just keep in mind that the needle biopsy is not 100% accurate!

Reference:
Accuracy of Fine-Needle Aspiration Biopsy for Predicting Neoplasm or Carcinoma in Thyroid Nodules 4 cm or Larger. Arch Surg. 2009;144(7):649-655. doi:10.1001/archsurg.2009.116.

False negatives in thyroid cytology: impact of large nodule size and follicular variant of papillary carcinoma. Laryngoscope. 2013 May;123(5):1305-9. doi: 10.1002/lary.23861. Epub 2013 Jan 4.

Impact of thyroid nodule size on prevalence and post-test probability of malignancy: A systematic review. Laryngoscope. 2015 Jan;125(1):263-72. doi: 10.1002/lary.24784. Epub 2014 Jun 26.


January 24, 2015

At-Home Influenza (Flu) Testing

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There are kits that can be purchased inexpensively over-the-counter to test for strep and mono. You can also add influenza (aka "the flu") to the do-it-yourself list, but unfortunately, this test kit is expensive at several hundred dollars on Amazon to perform 10-20 tests or about $20 per test.

Taking about 15 minutes to perform, these flu test kits are designed to detect Influenza A (including H1N1 virus) as well as the Influenza B virus antigens in nasopharyngeal specimens with over 90% accuracy. What exactly does nasopharyngeal mean? It requires advancing the culture swab all the way to the back of the nose... we are talking inches... not centimeters.



This requirement will probably dissuade most DIY patients, but if you can manage to get a good and accurate specimen, the rest of the steps for accurate test results is fairly straightforward and outlined below (depending on the kit purchased, instructions/steps may be slightly different):


Interpreting results is as follows (and contains internal controls which is nice):


Given flu is something that occurs yearly, this test kit may save money in the long run (over several years), especially for a family.

The average cost for the flu kit is around $200 for 10 test strips, or about $20 per test. This amount is less than the cost for most doctor visit copays, so if you find yourself making yearly doctor visits for flu symptoms and are willing to pay a large sum up front, this may be a worthwhile financial investment after several years.


At-Home Rapid Mono Testing

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Rapid mono test kits can be purchased by anybody to be done at home which may save parents/patients money in doctor visits as well as getting an answer right away. Indeed, should mono testing be positive, than you know that the patient is contagious... and that there's not much to do other than give it time to resolve. A doctor visit may still be worthwhile since there are other possible causes of a sore throat including strep throat, canceraphthous ulcersinus infectionreflux, etc.

Such home kits (which in fact are the same kits used in medical offices) can be purchased online through Amazon. The price is surprisingly affordable at around the cost of a single copay...  ~$40 to do 15 tests. There is also a rapid strep test kit that you can also purchase for about the same price as well as a rapid flu test kit.

However, with the purchase of such DIY kits, there are some pitfalls patients should be aware of if they decide to proceed. Essentially, you must follow the directions precisely, otherwise the test results will be unreliable. In other words, if the directions state to wait exactly five minutes to read the results, than one should wait literally 5 minutes... no longer or shorter.

For those who have done laboratory benchwork, the directions are reminiscent of performing a chemical experiment.

Should patients elect to start performing home mono testing, please be aware that physicians will be obligated to not only REPEAT the testing but also examine the patient to ensure no other issues are present.

1) Repeat testing is required because the patient may not have followed the instructions precisely resulting in an incorrect result. For example, the test cartridge must be read at 5 minutes (variable depending on the kit). If test results are read past 5 minutes, it may incorrectly show a positive result.
2) Some patients unfortunately fabricate test results just so they can get a certain treatment without an office visit.
3) Some patients unfortunately also fabricate test results in order to skip work or school for personal reasons not related to an actual medical condition.


January 20, 2015

How Accurate is Food Allergy Testing by Blood vs Skin Prick?

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A great new allergy research paper came out in Jan 2014 comparing the accuracy of skin prick versus blood testing for food allergies.

In summary, skin prick edges out blood testing in terms of accuracy, however mainly in terms of specificity. Sensitivity of both methods of testing is pretty comparable. However, blood testing tends to give more false-positives (test says you are allergic when you really aren't) compared to skin prick.

Blood testing may be more convenient and may provide a better guide to what one may be allergic to if you have no idea what possibly may have triggered an allergic reaction (one common scenario being having a reaction after eating at a Chinese all-you-can-eat buffet).

However, skin prick testing should be done if you are suspicious but not positive that you may be allergic to a certain food.

FYI... The BEST and MOST accurate food allergy testing is the oral food challenge... if you eat a certain food substance and you suffer an allergic reaction immediately afterwards, there's really no need for further testing as this type of "test" is the best and most accurate (oral food challenge). Remember, BOTH skin prick and blood testing do NOT provide 100% test accuracy.

In any case, here's a table comparing both methods of food allergy testing for a few things. Basically, the closer to 100%, the better the test.

Food Skin Prick
Sensitivity
Skin Prick
Specificity
Blood Test Sensitivity Blood Test Specificity
Cow's Milk
88%
68%
87%
48%
Egg
92%
58%
93%
49%
Wheat
73%
73%
83%
43%
Soy
73%
73%
83%
43%
Peanut
95%
61%
96%
59%
Hazelnut
88-90%
6-28%
75-99%
17-77%
Fish
91-100%
57%
67-94%
65-88%
Shellfish
100%
32-50%
100%
45%

References:
The diagnosis of food allergy: a systematic review and meta-analysis. EAACI journal Allergy. Article first published online: 14 DEC 2013, DOI: 10.1111/all.12333

January 18, 2015

Recurrent Infections of the Ear, Sinus May be Due to Immunodeficiency

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Image Courtesy of marcolm at FreeDigitalPhotos.net
Your immune system is what helps to fight off infections. But if the immune system is deficient in some way, a child or adult may experience recurrent infections. When it comes to ENT, such repeated infections may only involve the ear/sinus, or manifest itself as frequent URI.

What are some key questions that may prompt an investigation for an immunodeficiency, especially if surgical management fails to resolve?

• Need more than four courses of antibiotic treatment per year (in children) or more that two times per year (in adults)?
• Experience more than four new ear infections in one year after 4 years of age.
• Develop pneumonia twice over any time?
• Have more than three episodes of bacterial sinusitis in one year or the occurrence of chronic sinusitis?
• Need preventive antibiotics to decrease the number of infections?
• Develop unusually severe infections that started as common bacterial infections?

Specific to the ENT world, the main concern is whether there is an immunoglobulin deficiency. The algorithm put forth by AAAAI in this situation is outlined below.


What exactly is an immunoglobulin (Ig)?

They are specialized proteins that float around in the blood and tissues that attach to any germs it may  encounter. By attaching itself to germs, it brings attention for our cells to attack, kill, and remove. Consider it like a homing beacon.

However, if there are not enough immunoglobulins (Ig) floating around, than some germs may escape detection leading to recurrent infections.

There are 3 main types of Ig... IgG, IgA, and IgM.

As such, diagnosis typically entails to measure the amount of each present in the blood. If some numbers are unusually low, than immunodeficiency is present. A referral to an immunologist would be warranted at this point.

Even if serum Ig levels are normal, other types of immunodeficiency may be present... for example, there could be a cell defect such that it has trouble recognizing Ig or has impaired ability to kill and remove germs identified by Ig.

Indeed, there are over 180 different immunodeficiencies that have been identified so far. IgA deficiency is the most common disorder affecting 1 in 300-500 people.


References:
Practice parameter for the diagnosis and management of primary immunodeficiency. Ann Allergy Asthma Immunol 2005 May;94(5 Suppl 1):S1-63.
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