The Mysterious Lymphatic System

Just as most people don't know much about their spleens, they also know very little about their lymphatic system. Perhaps it's no surprise that the two are related? Both the spleen and the lymphatic system (with its vessels and nodes) play an important role in our immune response to disease and infections. Not to sound the hysteria alarm here, but without our lymphatic systems, we'd all turn into elephants, develop horrible infections and die.

What do elephants have to do with this? Well, as I discussed in a recent health tip about what can cause leg swelling,  I reminded us that a rare cause of leg swelling is damage to the lymphatic system. This damage is often caused unintentionally as a side effect of surgery, trauma, or radiation treatments. In some countries, tiny parasites are introduced into the body via mosquito bites, and they multiply inside the lymph vessels and nodes until they block them off completely. This results in a condition known as "elephantiasis" because the chronic back up of fluid into the extremities makes the legs look deformed and swollen - almost like an elephant leg. You can see a severe example at this website here.

The lymph system has two main roles: to remove excess fluid that the veins didn't capture and to circulate immune cells (called white blood cells) to fight infection and remove infectious debris from the tissues. You may have noticed swollen glands (or lymph nodes) in your neck when you had a throat infection. This is a good example of how the body attacks and clears infection - white blood cells are delivered to the site of a bacterial or virus invasion (such as your throat) and they kill the bad guys. Then the lymph system suctions up the liquid mess, sometimes transporting live cells and viruses to the next relay station (called a lymph node). If the infection war is still raging, the lymph node itself can become a swollen and tender battle ground. In the end, the lymph fluid is dumped into the bloodstream through neck veins and the body cleans the blood via the liver  and kidneys.

If you look at the drawing of the lymphatic system (picture above), you can see that it is spread throughout the entire body, so it can fight infections wherever they may crop up. Lymph nodes are mostly located deep inside the body and can't be felt with the finger tips. Neck, arm pit, and groin lymph nodes are exceptions - and this is why checking for swollen nodes in these areas are part of a doctors' physical exams.

So what does the spleen have to do with this? The spleen is considered to be part of the immune system because one of its functions is to produce white blood cells. These cells circulate in the lymphatic system, but they are manufactured in the spleen (and tonsils, intestinal wall, thymus gland, and bone marrow too.)

What can go wrong with the lymphatic system? 

1. Mechanical damage can disrupt the flow of lymph fluid, causing fluid back up and swelling.  The lymph vessels are very delicate (almost like spider webs), and their walls are not as tough as arteries or veins. They are therefore quite prone to injury by mechanical and compressive forces. The most common causes of lymphatic system injury are surgery, radiation, and trauma. Luckily the lymphatic system is a complex web that can usually find flow work-arounds. However, if there is extensive damage in a specific area, it can be overwhelming and result in swelling to the nearby limb (for example) previously served by that part of the system.
2. Cancer can plug up the system or cancer treatment can damage the lymphatics.  When white blood cells divide out of control and become cancerous, it makes sense that they can damage the circulatory lymph system where they live. Lymphoma is a cancer of the lymph system that directly damages it. Sometimes cancer spreads through the lymph system and travels to other parts of the body. When cancer gets into the lymph nodes, physicians sometimes have to cut those nodes out (lymph node dissections are common in breast cancer treatment, for example) or use radiation to burn the cancer. This can lead to chronic swelling issues in the arms or legs, known as lymphedema.
3. Parasites can block the lymphatic system.  As discussed earlier, certain parasitic worms have an affinity for the lymph system and although they can be killed with medicines, the damage they do to the lymph vessels and nodes may be permanent.

How do you keep the lymph system healthy? 

1. Regular exercise can help to reduce the amount of tissue edema and swelling that the veins and lymph system need to clear.
2. Treat lymph system damage early.  If you have swelling in an arm or leg from previous injury or cancer treatment, make sure you get treatment early. Reducing the length of time that the lymph system is over-taxed may decrease the long term damage. Kind of like a hernia - you should get it fixed sooner rather than later or it will just expand and get worse.
3. Avoid tight fitting clothes.  If you have lymphatic issues, compressing the area with tight clothing will only make things worse.
4. Physical therapy.  Some physical therapists (PTs) specialize in treating lymphedema. They have developed excellent massage techniques that can help to "milk" the lymph back to the blood circulation (called manual lymph drainage). They can also provide special wraps to reduce arm and leg swelling.

In my experience, physical therapy provides the very best treatment for lymphedema. With regular wrapping and manual lymph drainage, even elephant-like limbs can be returned to near-normal size. So although I raised a fairly scary prospect of life without our lymphatic system (in paragraph one), those who do have damage to their lymph systems should be encouraged: lymphedema specialist PTs will not let you become an elephant!

https://www.lymphnet.org/le-faqs/what-is-lymphedema/what-is-the-lymphatic-system

http://www.cancerresearchuk.org/about-cancer/what-is-cancer/body-systems-and-cancer/the-lymphatic-system-and-cancer

Health Tip: Is My Thyroid Gland Making Me Fat?

The thyroid gland is responsible for controlling our metabolism, and as such, it is often blamed for causing all manner of weight loss difficulties. Heck, I had my own thyroid hormone levels checked a few years back when my dieting wasn't producing the results I expected. In reality, though, only about 10% of women (and 1% of men) have low thyroid problems (or hypothyroidism). So it's not likely to be the primary cause of weight loss challenges, though it's important to diagnose and treat when present.

What do we mean by "metabolism" you might ask? It's the rate at which your body uses fats and carbohydrates, controls your body temperature, influences your heart rate, and regulates the production of protein. When your metabolism is slow, you tend to store food as fat rather than using it for energy.

What are the symptoms of hypothyroidism?
Honest-to-goodness low thyroid hormone can cause any or all of the following symptoms:
Fatigue, weakness, weight gain or increased difficulty losing weight, dry skin and hair, hair loss, increased cold sensitivity, hoarse throat, muscle cramps, joint pains, increases in "bad" cholesterol levels (LDL), constipation, depression, memory loss, irritability, and abnormal menstrual cycles. In severe cases of low thyroid hormone production, heart failure, coma, and death can occur.

Now you'll notice that many of these symptoms are fairly vague (and can be caused by many different things, including simple winter weather), which is why hypothyroidism often goes undiagnosed. It is reasonable, and fairly inexpensive, to check thyroid hormone levels if you are experiencing a number of these symptoms.

What causes hypothyroidism (low thyroid)?
The thyroid gland is located in your neck, just below the Adam's apple (or windpipe), and it can be damaged by inflammation, cysts or lumps (nodules), and (rarely) cancer. Autoimmune (or Hashimoto's) thyroiditis is the most common cause of thyroid gland damage. It is suspected that this happens during a viral or bacterial infection where the body is fighting off an invader, and in the process accidentally attacks the thyroid gland too. When the thyroid gland is damaged, it produces less (or no) thyroid hormone, resulting in a decrease in the metabolic rate of cells throughout the body.

What causes hyperthyroidism (high thyroid)?
In the opposite case, the thyroid gland may produce too much hormone. Inflammation caused by autoimmune disease (Grave's disease), infections, and non-cancerous nodules can all trigger the gland to produce too many hormones. This can results in feelings of anxiety, nervousness, sweating, bulging eyes, trembling, rapid heart rate, skin changes and irritability.

The confusing thing is that inflammation of the thyroid gland can cause either high or low hormone output. And sometimes, the gland responds at first with high output and then eventually "burns out" and ends up not producing much hormone at all. In addition - procedures aimed at treating overactive thyroid (such as radioactive iodine or surgery) can overshoot, resulting in low thyroid hormone levels in the long run.

Not to confuse you further, but thyroid hormone levels are also regulated inside the body by two other glands located in the brain (the pituitary gland and hypothalamus). If something goes wrong with either of those two glands (or their messaging systems), it can disturb the delicate metabolic balance of the entire body.

Now one last thing I have to mention - thyroid hormone production depends on iodine. Iodine is found in our diet in the form of seafood, beans, and certain fruits and vegetables. In the United States we supplement table salt with iodine, which has virtually solved the low iodine problem for us. However, 40% of the world's population is at risk for iodine deficiency, which can cause normal thyroid glands to be unable to produce their hormones. This results in goiters (enlarged, but non-functional thyroid tissue).

How do I keep my thyroid healthy?
The truth is, outside of getting enough iodine in your diet, there isn't much you can do to prevent thyroid problems. Autoimmune diseases and infections, adenomas (hormone-producing lumps in the thyroid gland), and cancer can't readily be avoided. Genetics and "luck" are generally the determinants of thyroid health (though exposure to neck radiation - from previous cancer treatment for example - is a risk factor as well). That being said, though, if you have symptoms of an overactive or underactive metabolism, it is easy enough to check your thyroid hormone levels with blood tests. The good news is that thyroid hormone can be taken in pill-form if you are in short natural supply. If you have an overactive thyroid, surgery and/or radiation can be curative.

If you find a lump in your neck (in the area of your thyroid gland) see your doctor to have it checked out. Most of the time (about 90%), these lumps are not cancerous, but are capable of over-producing thyroid hormone. Ultrasound tests, observation, or needle biopsy may be recommended for further evaluation.
In my clinical experience with patients, thyroid hormone replacement can be tricky and frustrating. Even though we can correct low thyroid hormone levels with supplements (such as Synthroid or levothyroxine) so that blood tests look "normal," patients often tell me that they are still fatigued and are not feeling themselves. Some patients respond better to brand-name (rather than generic) thyroid drugs. In these cases I often refer them to a thyroid specialist (endocrinologist) who can further assist with medication optimization. Thyroid hormone levels (and the body's internal control of them through the pituitary gland and hypothalamus) are actually really complicated - so if you have thyroid disease that you don't feel is being adequately managed by your primary care physician or thyroid surgeon, don't be shy to seek help from an endocrinologist. I do it for my patients all the time!

Now that you've had a health tip introduction to most of the major body parts and systems - you are ready to ask questions! Please feel free to send your questions to me at weeklyhtblog@yahoo.com and I will do my best to answer them for all to see!

References
http://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/dxc-20155382
http://www.mayoclinic.org/diseases-conditions/hyperthyroidism/basics/causes/con-20020986
https://www.thyroid.org/iodine-deficiency/#table1
http://www.cancer.net/cancer-types/thyroid-cancer/risk-factors
https://www.cancer.org/cancer/thyroid-cancer/about/what-is-thyroid-cancer.html

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Health Tip: What Causes Leg Swelling?

In my last health tip I described how blood is circulated around the body. I mentioned that poor circulation can cause leg swelling, and promised to provide a fuller review of this very common problem. I'd venture to say that almost 100% of adults have noticed puffiness or swelling in their legs at some point - so what is going on?

Probably the most common cause of leg swelling is compression of the large thigh veins that return blood to the heart. When we sit in a chair, our body weight presses on our veins, and the edge of the hard seat puts extra pressure on the back of our thighs. When the blood's "pipes" are narrowed, pressure backs up the blood into the feet where gravity also contributes to its pooling. Under higher pressures, some of the water content of the blood leaks through the blood vessels into the nearby potential space between muscles and skin and into fatty tissue. This results in a swollen appearance of the legs.

Prolonged sitting (which occurs in long car trips or airplane flights) contributes to leg swelling, especially if you do not get up and walk around at regular intervals. Calf muscles help to milk venous blood back to the heart when they contract, so simple walking can make a big difference in improving swelling. Elevating the legs can reduce the effect of gravity, which also helps to reduce puffiness.  If you're stuck in a car or airplane (or any chair, frankly) for a long period of time, foot pumps are the best exercise (outside of walking) to get those calf muscles working. You can view the most effective leg exercises here.  Although doctors have not yet determined the optimal frequency of leg exercises when you're stuck in a chair, I'd say moving your legs every 30 minutes to an hour is a good idea. Leg swelling can be a sign that you're at risk for blood clots [Arteries And Veins: What is The Difference?], and you definitely want to avoid those at all costs! If only one leg is swollen, that can be a sign that there is already a clot in a large leg vein, so you should see a doctor right away if this happens.

Most leg swelling is related to a mix of body position, inactivity, and gravity. However, anything that reduces pressure in the circulation can cause blood to pool in the legs. If the heart is not pumping strongly, for example, it can't force the blood all the way around the system. Heart failure results in leg swelling as the blood pools in the farthest point from the heart muscle, and gravity contributes to keeping it there.

Interestingly, blood needs a certain amount of protein content to remain inside the blood vessels. I think of it kind of like the difference between trying to keep pudding on a fork versus milk on a fork. The pudding will probably stay put, despite the gaps, but the milk is too thin and falls right through. Our smallest blood vessels are intentionally leaky to allow transport of nutrients and oxygen through (they have walls like a fork - to use my analogy) but the walls will let water through too if the blood is too thin or pressure is too high. Conditions that reduce the protein content of blood (such as malnutrition or liver failure) can cause leg swelling. This is why physicians encourage protein supplements (such as Ensure milkshakes) in elderly or sick people who are not eating enough.

Kidneys filter the blood and remove part of its water content in urine (please see my previous health tip about how kidneys work). [Kidneys: What Do They Do and How Can You Keep Them Healthy?] If the kidneys are significantly damaged, they stop filtering the blood and it becomes swollen with extra fluid, which increases the pressure in capillary beds and water forces its way through the fork tines, causing swelling.
Inflammation (due to allergy, auto-immune reaction, or infection) can also cause swelling through a different mechanism. Certain cells responsible for allergy or infection responses produce chemicals (such as histamines) to attract white blood cells to the affected area. The chemicals trigger local blood vessels to become more leaky (like spreading apart the fork tines) to encourage transport of white cells through the blood vessel walls and into the nearby tissues.

When the area of inflammation is small (such as bug bite, or sinus infection), the local swelling doesn't present much of a problem. However, when an infection that has gotten into your blood stream (often referred to as sepsis - the old fashioned term is "blood poisoning"), all the blood vessels in the body are exposed to the chemicals that tell them to become leaky, and they do so all at once. This results in a massive shift of the blood's water content into the tissues, drops in blood pressure, and potential death. This is why doctors like to treat infections early on, because once sepsis sets in, it's very hard to tighten up the fork tines and get fluids back where they belong before the patient becomes unconscious and needs mechanical ventilation. Any infection (such as pneumonia, cellulitis, diverticulitis, urinary tract infections, etc.) has the potential for spreading into the blood stream and causing sepsis (which also causes massive swelling often visible in the arms and legs and face) and is life-threatening.

The final main cause of leg swelling that I will mention is lymphedema. The lymph system provides back up to the circulatory system by suctioning extra blood plasma (that has leaked out of the capillaries) out of the tissues and returning it to the heart through little relay stations called "lymph nodes" and then dumping it into the neck veins. If this system is blocked or damaged (most commonly due to previous surgery or radiation treatments and sometimes tumors or blood cancer), the blood's water remains outside the blood vessels and causes swelling.

In some countries outside the United States, parasites can cause blockage of the lymph system (the infection is known as filariasis, caused by 3 different species of tiny worms that can enter the body via a mosquito bite and multiply inside lymph nodes) which can result in massive leg swelling known as elephantiasis (in severe cases, human legs can look a lot like an elephant's, hence the name!)

In summary, leg swelling is usually harmless and reversible (from venous compression) but can be a sign of something more serious (such as heart, kidney or liver failure, protein malnutrition, or advanced infection). Regular exercise, a nutritious diet, and maintaining a healthy body weight can all help to reduce the risk of blood clots from leg swelling.

In my next health tip, I'll review the lymph system because, like the spleen [The Spleen: Least Useful Organ In The Human Body?], it's quite mysterious to most people and yet - without a functioning lymph system you could almost literally turn into an elephant!

References
http://www.mayoclinic.org/symptoms/leg-swelling/basics/causes/sym-20050910
https://rarediseases.org/rare-diseases/elephantiasis/

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Arteries And Veins: What is The Difference?

Most non-medical people don't know the difference between an artery and a vein, and the confusion is quite understandable. The truth is, arteries and veins connect to each other and are part of a circuit that transports blood from the heart to the rest of the body (arteries) and back to the heart again (veins). Arteries are the tubes that contain freshly oxygenated blood pumped from the heart to the body, and veins are the tubes that transport the blood back to the heart. Between the two are tiny little branches that form a mesh network of blood vessels (called capillary beds) with delicate little walls that allow oxygen and nutrients to be transported across them and into the cells nearby.

Arteries and veins have important differences in their wall structures. Arteries have to be tough and strong to withstand the high pressure of the heart's pump. Their walls are muscular and thick, and don't allow things to pass through. Over time, arteries can "harden" and develop deposits of cholesterol and calcium in their walls. If they become too narrow, or if the deposits tear off and form a clot, the tissue they supply downstream can have its oxygen supply suddenly stopped. This results in the potential for that tissue to suffocate and die. If the tissue downstream from the clot or artery narrowing is brain, the result is a stroke, if the tissue is heart muscle, the result is a heart attack. Any tissue can be affected (including the eyes, lungs, and limbs) by artery narrowing or clot formation, but brain and heart damage occur most commonly.

It's important to recognize heart attack and stroke symptoms right away because doctors can often remove clots with medicines (kind of like Drain-O) or open the arteries back up with small surgical procedures (like a Roto-Rooter) before the downstream tissue outright dies. It breaks my heart when I hear patients tell me that they were having chest pain or sudden weakness of half of their body so they decided "to lie down and rest" in the hope that it would go away. Unfortunately, if the blood supply is not restored to the brain or heart within 6 hours, the cells will die and recovery is severely limited. While my patients were "resting" they were allowing their brain or heart tissue to suffocate. So please don't be like them - get medical help immediately if you have symptoms of a stroke or heart attack.

As far as veins are concerned, they are a collecting system for the blood returning to the heart from the capillary beds. Their walls don't have to be tough, they are soft and collapsible. The blood pressure in veins is so low that they have little valves in them that help to prevent blood from pooling in the feet, for example. When nearby muscles contract, they tend to compress the veins and "milk" the blood back towards the heart. When the blood passes a valve, it flops closed so the fluid can't slide backwards. For this reason, inactivity can cause swelling in the legs. When calf muscles are not working, squeezing the veins and passively milking the blood back to the heart, the blood tends to pool in the legs (especially if they are dangling - gravity contributes) and the higher pressure allows the water portion of the liquid blood to leak out of the veins and capillaries and puff up the skin and surrounding tissues.

Some people are born with faulty valves in their veins, and this can contribute to "varicose vein" problems. Veins with herniated walls look lumpy and can be seen through the skin. Superficial veins can be surgically removed (sclerotherapy) to improve the cosmetic appearance, and the blood simply returns to the heart through veins that are deeper in the muscle and not visible from the surface.

Veins can also develop clots when the blood is not moving through them fast enough (it congeals). When clots develop in the large veins of the legs, they are called DVTs (or deep vein thrombosis) or VTEs (venous thrombo-embolism). These clots are dangerous because they can break free from the leg vein and travel in the bloodstream back to the heart and get pumped into the lungs. When a clot is stuck in a lung, it cuts off the blood supply and that part of the lung will permanently die unless the clot is removed right away. In rare cases, people who have a small heart defect can get a stroke from leg vein clots traveling through the heart to the brain.

So as you can see, both arteries and veins are important blood transport tubes that can cause a lot of trouble if they are narrowed or clotted off. What can you do to keep your arteries and veins in good health?

1. Exercise - regular exercise is the very best way to keep your muscular arteries and your floppy veins moving blood through the system. I think of exercise as kind of a natural flushing mechanism for the arteries and veins. You wouldn't want to leave your toilet unflushed for more than a day or two, and neither should you go very long without exercise! The optimal amount of exercise depends on your medical status, but for most Americans, 30-60 minutes of moderate-intensity exercise (five days per week) or 20-60 minutes of vigorous-intensity exercise (three days per week) is recommended. Remember, walking is great exercise because the calf muscles will naturally milk the leg blood back to the heart!
2. Maintain a healthy weight - as you can imagine, having extra fat makes the heart work harder to push blood through that tissue. Veins may be compressed by extra body fat and have a hard time getting blood back to the heart, causing swelling and water weight gain, and even skin break down.
3. Get your cholesterol checked - cholesterol can build up in the artery walls over time, making them narrower, and creating plaque that can break off and cause heart attacks and strokes. How your body processes cholesterol is determined by your genetics, so there are some people who really can't control their cholesterol with a healthy diet alone. Your doctor will let you know if you should take a cholesterol-lowering medication.
4. Don't take high doses of calcium supplements - we have recently discovered that calcium pills may do more harm than good for some (especially older) people. Although calcium is important for maintaining strong bones, too much of it can cause the body to store it in the artery walls! It's much safer to get your calcium from food sources, so if you're supplementing your diet with calcium pills, ask your doctor if the benefits outweigh the potential risks for you.
5. Take blood clots seriously - if you have a swollen, tender calf and a sedentary lifestyle, check with your doctor to see if you should be tested for DVTs. Once diagnosed with a blood clot in your leg, be very vigilant to take your clot busting (or blood thinning) medicines as directed. You do not want the clot to travel to your lungs (called a pulmonary embolism).
6. Treat your auto-immune disease - some people have auto-immune reactions that involve their blood vessels. Inflammation of the blood vessels puts them at a high risk for clots, and so it's especially important for people with vasculitis to follow their doctor's medical advice and take medicines on time.

In my next health tip, I'll discuss a common problem: leg swelling. A patient of mine recently asked me what could cause swollen legs, and it made for a good discussion. You have learned some of the potential causes in this review (clots, vein insufficiency, inactivity, gravity) but there are quite a few more that I think you'll find interesting.

References
http://www.acsm.org/about-acsm/media-room/news-releases/2011/08/01/acsm-issues-new-recommendations-on-quantity-and-quality-of-exercise
http://www.hopkinsmedicine.org/news/media/releases/calcium_supplements_
may_damage_the_heart

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