Dear Doctor: My ex-wife was seeing a primary care doctor who also treated her heart issues, which were not of a serious nature. She sought a second opinion from a specialist, which prompted her own doctor to unceremoniously drop her as a patient, without even informing her. She found out the next time she called for an appointment. Is this ethical -- or even legal?

Dear Reader: One of the most satisfying elements of a physician's job is helping a patient. That sense of satisfaction, along with the respect for the profession and praise from our patients, can infuse a physician's sense of self-worth, potentially inflating the ego of even the most humble physician. Conversely, when a patient is unhappy with a doctor or when a doctor's diagnosis proves to be incorrect, a physician can question his or her ability and value. And, of course, doctors -- like everyone else -- have biases, personality quirks, stressful days and distractions caused by many nonwork factors. In short, doctors are people too.

I don't know whether your ex-wife and her primary care doctor had a good, long relationship or a short one marked by poor communication. But a strong primary care relationship is essential to overall high-quality medical care. A primary care doctor is the physician you see for physicals, and the first doctor you see for colds, injuries and many other maladies. Because of this, such physicians often have a deeper understanding of the whole patient than would a short-term specialist, and they take that position seriously. When a patient seeks a new primary care doctor, or seeks the advice of a specialist without the other doctor's knowledge, the doctor might feel that his or her care was considered inadequate.

When that happens, some doctors may feel that it's an attack upon their self-worth and will act in a defensive way. Others are more deferential, realizing that they can't help or please everybody. These doctors don't feel threatened by opinions from other physicians.

Obviously, I don't know what transpired in the mind of your ex-wife's primary care doctor -- and I'm not defending his or her actions. A conversation that sought to identify any potential concerns on her part would have been a better way of handling the perceived slight. That said, a doctor has every right to fire a patient for not following recommendations, rude behavior or missing multiple appointments.

As for the legality of the doctor's actions, laws in many states penalize doctors who abandon patients needing specific medical care. That means if a patient is in a medical crisis, it is incumbent upon the doctor to either take care of the patient or find an immediate alternate provider. In writing a discharge letter from a practice, a doctor usually gives a 30-day window, giving the patient time to find a new doctor and obtain medication refills. Clearly, the doctor should have provided a warning letter or a letter of discharge.

The relationship between doctor and patient is fraught with the difficulties of human interaction. A poor relationship with a primary care doctor can lead to bad outcomes, regardless of who is primarily at fault. Dissolving the relationship under these circumstances may be for the best.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers! How is 2018 treating you so far? Thank you, as ever, for your emails and letters. Your kind comments warm our hearts; your criticisms make us want to do better; and your questions, comments and opinions widen our worldview. And on that note, onward!

-- After our column about teething remedies was published, we received quite a few questions regarding the purported benefits of amber teething necklaces. These necklaces have become popular teething aids in some parts of the country. Amber, which is fossilized tree resin, has long had a role in folk medicine. When it comes to teething, the idea is that the succinic acid contained in Baltic amber will be absorbed via the skin and confer therapeutic effects.

While it's true that Baltic amber does contain small amounts of succinic acid, we were unable to find any research that shows it acts as an analgesic, that body heat will cause it to be released or that it can be absorbed through the skin. Even if the above were possible, the dose of succinic acid available in an amber necklace would be miniscule. Add in the choking hazard presented by the size of the amber beads and a recent study that found these necklaces to be associated with bacterial colonization, and our position is that the very real risks outweigh the unproven benefits.

-- A recent column about portion control showed us how creative you readers are. The range and variety of visual guidelines you use for portion control has been fascinating to see. We particularly liked this whole-plate approach to making sure a meal doesn't stray into overeating:

"Make it simple," writes Noreen, who uses a small salad plate as her template. She fills two-thirds of the plate with vegetables, then fills the remaining space with meat or a meat substitute, and a serving of fruit. Noreen reverses the typical American approach and eats her largest meals at breakfast and lunch and goes light on dinner.

-- And, finally, thank you to a reader for adding to our discussion of urinary incontinence.

"You have mentioned stress incontinence in your column a couple of times recently, but I don't recall that there was any mention of obesity as a contributing factor," our reader points out. "If weight loss can be part of treatment for UI, it would be helpful to know for people who have both of those conditions."

You're right -- a number of studies have shown a clear link between obesity and urinary incontinence. Individuals who are overweight experience an increase in intra-abdominal pressure. This has the effect of increasing pressure on the pelvic floor, including the bladder and the bowel, and plays a role in developing urinary incontinence, or UI.

The good news is that several studies have shown that weight loss can significantly reduce the number of stress incontinence episodes experienced by participants. In fact, weight loss, along with exercise, is recommended as a first-line treatment for urinary incontinence among individuals who are significantly overweight.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I recently read about a sugar additive being linked to the rise of a killer bug. What is this additive, how do I avoid it, and how serious is the threat?

Dear Reader: Clostridium difficile, or C. diff, is a bacterium that can cause severe intestinal infections, leading to severe diarrhea, possible hospitalizations and even death, especially in people over the age of 65. Antibiotic use is often the precipitating factor in C. diff infections because the drugs kill off the normal bacterial populations in the colon and allow for C. diff to multiply and release toxins, triggering inflammation and diarrhea. Rates of C. diff infection are increasing in this country, with nearly 500,000 people per year affected and 15,000 deaths. Use and overuse of antibiotics are blamed for this increase. But a recent study in the journal Nature may point to another factor.

First, note that C. diff has different subtypes, or ribotypes, with two strains in particular -- RT027 and RT078 -- associated with large outbreaks of disease. These outbreaks have been common since the year 2000. The year is important because that's when the sugar trehalose became available for mass production and began to be readily placed in foods and drinks. Of course, many notable things occurred in the year 2000, so let's explore how a sugar product could specifically be blamed for an increase in the risk of C. diff outbreaks.

Trehalose is a naturally occurring sugar produced by plants, fungi, bacteria and insects that helps organisms retain water and prevents cellular damage when there is no water. It's about 45 percent as sweet as sucrose (or table sugar), but researchers for years lacked a cost-effective way to extract it. However, in 2000, a new enzymatic extraction method led to a cheap way to mass-produce trehalose. Subsequently, many food products and drinks were produced with this sugar as an ingredient.

The study you are referencing looked at how the C. diff ribotypes RT027 and RT078 respond to trehalose. For starters, RT027 will grow five times greater than other ribotypes of C. diff when trehalose is a food source. Also, RT027 needs lower concentrations of trehalose to turn on enzymes that metabolize the sugar. Mice infected with the RT027 type were three times as likely to die when given a solution that mimicked human intake of trehalose compared with those given water. The ribotype RT078 also shows an increased ability to metabolize trehalose.

Further, the small intestine doesn't absorb trehalose as well as it does sucrose. This leads to more trehalose ending up in the large intestine, which is where C. diff causes its damage. Thus, if a patient has an RT027 or RT078 strain of C. diff and trehalose is present in the large intestine, the bacteria can readily use trehalose to survive and multiply. These bacteria will also have a competitive advantage over other bacteria in the colon that cannot utilize trehalose.

It's one of those quirks of nature that a bacterium can use a naturally occurring substance to its benefit -- and our detriment. I would look at food labels and evaluate whether your diet is high in this sugar. If so, you might want to make adjustments. The data are concerning.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)