Systemic lupus erythematosus

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Systemic lupus erythematosus

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Questions

USMLE® Step 1 style questions USMLE

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A 38-year-old woman comes to the clinic complaining of pain in her hands for several months. The pain is characterized by an intermittent aching in both of the wrists and the bases of the fingers that lasts for hours at a time. The patient also feels warm at night and has not had much of an appetite recently. The patient’s temperature is 37.6 C (99.6 F), pulse is 77/min, respirations are 14/min, and blood pressure is 145/85 mmHg. Physical examination shows mild symmetric swelling of the wrists, metacarpophalangeal, and proximal interphalangeal joints bilaterally, without tenderness on palpation. There are no skin lesions. Laboratory studies show the following:  
 
Laboratory value  Result
 Hemoglobin  14.0 g/dL 
 Platelets  100,000/mm3 
 Leukocytes   3,500/mm3 
Further evaluation with urinalysis shows proteinuria and red blood cell casts.    

Which of the following is the most common cause of death in patients with this condition?  

External References

First Aid

2024

2023

2022

2021

Anti-dsDNA antibody p. 113

Arthritis p. 472

lupus p. 476

Lupus

anemia of chronic disease and p. 427

autoimmune hemolytic anemia and p. 415

azathioprine for p. 443

drug-induced p. 113

isoniazid p. 194

lab/findings p. 729

lymphopenia p. 429

microangiopathic anemia p. 415

neutropenia p. 429

presentation p. 724

Lupus-like syndrome

α-methyldopa p. 242

hydralazine p. 323

procainamide p. 326

Lupus pernio p. 695

Phenytoin

drug-induced lupus p. 249

Skin lesions

lupus pernio p. 695

SLE (systemic lupus erythematosus)

acute interstitial nephritis p. 620

autoantibodies p. 113

DPGN p. 616

HLA subtypes p. 98

kidney disease with p. 612, 616, 620

Systemic lupus erythematosus p. 476

Raynaud phenomenon p. 479

“Wire lupus p. 616

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Content Reviewers

Alright, “systemic lupus erythematosus,” k we totally got this. “Systemic” is easy, and refers to affecting multiple organs in the body.

“Erythematosus” means reddening of the skin, alright alright.

Lupus” is latin for “wolf”. So affects multiple organs wolf...reddening of the skin?

Not exactly, the modern use of lupus usually refers to a variety of diseases that affect the skin...which was possibly originally used since these diseases resemble a wolf bite on the patients’ skin.

Is that true? Who knows. At any rate, systemic lupus erythematosus, or SLE, sometimes just lupus, is a disease that’s systemic, and affects a wide variety of organs, but notably often causes red lesions on the skin.

But how does lupus affect all these organs? Well usually the immune system protects the body’s tissues from invaders, but lupus is an autoimmune disease, which means that immune cells start attacking the very tissues their supposed to protect.

With lupus, essentially any tissue or organ can be targeted.

And just like a ton of other autoimmune diseases though, it’s not completely clear why it develops, and like most diseases it’s the result of both genetics and the environment.

Alright so let’s go over a specific scenario to show how this plays out.

Let’s say this guy has susceptibility genes—genes that make him susceptible to getting lupus, and he’s exposed to UV radiation in sunlight, which we know is an environmental risk factor for lupus.

Well, given enough UV rays, think like sunburn, the cell’s DNA can become so badly damaged, that the cell undergoes programmed cell death, or apoptosis, and it dies.

This produces all these little apoptotic bodies, and exposes the insides of the cell, including parts of the nucleus, like DNA, histones, and other proteins, to the rest of the body.

Well those susceptibility genes specifically have an effect on this person’s immune system such that their immune cells are more likely to think that these are foreign, or antigens, and since they’re from the nucleus, we call them nuclear antigens, and immune cells try to attack them.

Not only that though, susceptibility genes also cause this person to have less effective clearance, essentially they aren’t as good at getting rid of the apoptotic bodies and so they end up having more nuclear antigens floating around.

This means that B cells might swing by, see them, and start the production of antibodies against these pieces of nucleus, which are called antinuclear antibodies, and these guys are present in almost all cases of lupus.

Summary

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease in which the body's immune system mistakenly attacks healthy tissue. SLE most often harms the heart, joints, skin, lungs, blood vessels, liver, kidneys, and nervous system. Common symptoms of SLE can include fatigue, joint pain, rash, fever, and anemia. The course of the disease is unpredictable, with periods of illness (called flare-ups) alternating with remissions. Treatment typically involves medications to manage symptoms, reduce inflammation, and suppress the immune system.