Systemic disease in the context of Diplopia

Septicemic plague is one of the three forms of plague, and is caused by Yersinia pestis, a gram-negative species of bacterium. Septicemic plague is a systemic disease involving infection of the blood and is most commonly spread by bites from infected fleas. Septicemic plague can cause disseminated intravascular coagulation and is always fatal when untreated. The other varieties of the plague are bubonic plague and pneumonic plague.

The Great Imitator (also the Great Masquerader) is a phrase used for medical conditions that feature nonspecific symptoms and may be confused with a number of other diseases. The term connotes especially difficult differential diagnosis, increased potential for misdiagnosis, and the protean nature of some diseases. Most great imitators are systemic in nature or have systemic sequelae, and an aspect of nonspecific symptoms is logically almost always involved. In some cases, an assumption that a particular sign or symptom, or a particular pattern of several thereof, is pathognomonic turns out to be false, as the reality is that it is only nearly so.

As recently as the 1950s, syphilis was widely considered by physicians to be "the great imitator", and in the next few decades after that, several other candidates, mainly tuberculosis but occasionally others, were asserted as being "the second great imitator". But because differential diagnosis is inherently subject to occasional difficulty and to false positives and false negatives, the idea that there are only one or two great imitators was more melodrama than objective description. In recent decades, more than a dozen diseases have been recognized in the medical literature as worthy of being considered great imitators, on the common theme of recurring misdiagnoses/missed diagnoses and protean manifestations. Nonetheless, not every caveat (not every mimic) meets the threshold, because it is inherent to differential diagnosis generally that there are thousands of caveats.

Diplopia is the simultaneous perception of two images of a single object that may be displaced in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occurring involuntarily, it results from impaired function of the extraocular muscles, where both eyes are still functional, but they cannot turn to target the desired object. Problems with these muscles may be due to mechanical problems, disorders of the neuromuscular junction, disorders of the cranial nerves (III, IV, and VI) that innervate the muscles, and occasionally disorders involving the supranuclear oculomotor pathways or ingestion of toxins.

Diplopia can be one of the first signs of a systemic disease, particularly to a muscular or neurological process, and it may disrupt a person's balance, movement, or reading abilities.

Nephrology, from Ancient Greek νεφρός (nephrós), meaning "kidney", and λόγος (lógos), meaning "study", is a specialty for both adult internal medicine and pediatric medicine that concerns the study of the kidneys, specifically normal kidney function (renal physiology) and kidney disease (renal pathophysiology), the preservation of kidney health, and the treatment of kidney disease, from diet and medication to renal replacement therapy (dialysis and kidney transplantation). The word "renal" is an adjective meaning "relating to the kidneys", and its roots are French or late Latin. Whereas according to some opinions, "renal" and "nephro-" should be replaced with "kidney" in scientific writings such as "kidney medicine" (instead of "nephrology") or "kidney replacement therapy", other experts have advocated preserving the use of renal and nephro- as appropriate including in "nephrology" and "renal replacement therapy", respectively.

Nephrology also studies systemic conditions that affect the kidneys, such as diabetes and autoimmune disease; and systemic diseases that occur as a result of kidney disease, such as renal osteodystrophy and hypertension. A physician who has undertaken additional training and become certified in nephrology is called a nephrologist.

Delayed puberty is when a person lacks or has incomplete development of specific sexual characteristics past the usual age of onset of puberty. The person may have no physical or hormonal signs that puberty has begun. In the United States, girls are considered to have delayed puberty if they lack breast development by age 13 or have not started menstruating by age 15. Boys are considered to have delayed puberty if they lack enlargement of the testicles by age 13.5 . Delayed puberty affects about 2% of adolescents.

Most commonly, puberty may be delayed for several years and still occur normally, in which case it is considered constitutional delay of growth and puberty, a common variation of healthy physical development. Delay of puberty may also occur due to various causes such as malnutrition, various systemic diseases, or defects of the reproductive system (hypogonadism) or the body's responsiveness to sex hormones.

An ocular manifestation of a systemic disease is an eye condition that directly or indirectly results from a disease process in another part of the body. There are many diseases known to cause ocular or visual changes. Diabetes, for example, is the leading cause of new cases of blindness in those aged 20–74, with ocular manifestations such as diabetic retinopathy and macular edema affecting up to 80% of those who have had the disease for 15 years or more. Other diseases such as acquired immunodeficiency syndrome (AIDS) and hypertension are commonly found to have associated ocular symptoms.

A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of prolamin proteins found in wheat (and all of its species and hybrids, such as spelt, kamut, and triticale), as well as barley, rye, and oats. The inclusion of oats in a gluten-free diet remains controversial, and may depend on the oat cultivar and the frequent cross-contamination with other gluten-containing cereals.

Gluten may cause both gastrointestinal and systemic symptoms for those with gluten-related disorders, including coeliac disease (CD), non-coeliac gluten sensitivity (NCGS), and wheat allergy. In these people, the gluten-free diet is demonstrated as an effective treatment, but several studies show that about 79% of the people with coeliac disease have an incomplete recovery of the small bowel, despite a strict gluten-free diet. This is mainly caused by inadvertent ingestion of gluten. People with a poor understanding of a gluten-free diet often believe that they are strictly following the diet, but are making regular errors.