Pediatrics
[IMMUNODEFICIENCY]
In any baby with recurrent infections , prolonged infections , or infections with weird bugs there should be an increased index of suspicion for an immunodeficiency. Since maternal antibodies are present for about 6 months after birth it’ll be hidden until they wear off. In general, unless there’s a high index of suspicion based on a clinical exam the first step is usually Immunoglobulin Immunoglobulin Levels with a CBC (white count). This will provide evidence for sufficient numbers of both cells and immunoglobulins. After that it’s up to you to get the specific tests or slides to definitively diagnose. While the basic sciences will will tell us that certain certain cells are designed designed to fight fight certain certain infections (B cells Bacteria, T cells fungus ), there’s no correlation with the bug infecting and the underlying diagnosis. B-CELLS
X-Linked Agammaglobulinemia of Bruton It’s an X-linked disorder (only boys get it) of a B cell deficiency in boys . Recurrent “normal” infections ( sinusitis / otitis / pneumonia) are often frequent or severe. Get the Ig Levels; this disease will be apparent as All immunoglobulins are deficient (IgM, IgG, IgA). cells. Confirm the diagnosis with ↓B cells and a compensatory ↑T cells Patients will need prophylactic antibiotics and monthly immunoglobulins . If it’s a kid older than 15 on first presentation consider combined mixed tissue disorder rather than Bruton’s. IgA Deficiency This is the most common and most benign of the immunodeficiencies. IgA protects against the mucosal barrier so patients may have respiratory or GI infections infections. However, IgM still works so these patients may never be diagnosed at all. The big red flag is a patient who gets an anaphylactic reaction after blood transfusion from exposure to the new (and foreign) IgA. Hyper IgM Deficiency When Ig levels are gotten due to immunodeficiency suspicion, there’ll be low levels of IgA and IgG, but with a compensatory increase in the IgM. Differentiation doesn’t occur, but the body is still able to do some defending with the less selective IgM. B-CELLS
DiGeorge Syndrome The thymus and facial structures come from the 3rd pharyngeal pouch. With deficiency of the 3rd pouch, there’ll be: micrognathia, wide-spaced eyes, low-set ears, and absent thymic shadow (the syndrome). This disease can be suspected on the baby’s physical appearance, but any fungal or Pneumocystis Pneumonia should be a huge red flag. There may be an underlying cardiac defect that has to be identified. identified. Start by giving antibiotics and prophylaxis against PCP (Bactrim/Dapsone). Cure by giving the baby a thymic transplant . If the facial structures lead to thinking about DiGeorge, pay close attention to the calcium; absent parathyroid glands can produce hypocalcemia (and seizures).
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Pediatrics
[IMMUNODEFICIENCY]
Wiskott-Aldrich In boys (because it’s X-linked ) with (1)normal bugs infections , (2) thrombocytopenia , and (3) eczema, think Wiskott-Aldrich. There’ll be ↑IgE and ↑IgA on immuno-studies. Patients may need bone marrow transplants but they rarely survive to adulthood. Without Bs or Ts the body gets eaten by everything. Ataxia-Telangiectasia Yeah, you’ll see this. Not. Know “Telangiectasias + Ataxia, DNA repair, lymphoma, leukemia. ” Never suggest this to an attending unless it’s Dr. House. Pick it on the exam. It’s incredibly rare. SCID The kid has no immune system. Knowing that this can be caused by adenosine deaminase deficiency was required for step I. Now, realize that he/she basically has AIDS. He/she gets infected with AID bugs and gets AIDS diseases, yet there’s no viral load / viral infection. It’s just like AIDS so he/she needs PCP and MAC prophylaxis (Bactrim, Azithromycin). To cure, get a bone marrow transplant. Chronic Granulomatous Disease Macrophages can eat but not kill organisms that are catalase . When chronic skin (staph) or aspergillus infections are seen think of this. The body knows there’s an infection - antibodies are produced (↑IgM and IgG) and cells are dispatched (↑ WBC) – it’s just that the cells can’t do anything. Confirm with a negative nitro blue test that reveals an absent respiratory burst. Organisms that produce their own H2 O 2 can be killed. Leukocyte Adhesion Deficiency Neutrophils cannot adhere or get out of the blood vessels. Thusly there’s no pus despite a massive leukocytosis and high fever (↑ cytokines, antibodies, and leukocytosis in response to infection). An early sign (that will give the diagnosis away in a vignette) is delayed separation of the cord . Get a Bone Marrow Transplant. Chediak-Higashi It’s an Autosomal recessive disorder leading to impaired microtubule polymerization . It will also show albinism , neuropathy , and neutropenia. Look for giant granules in neutrophils . C5-C9 (Terminal Complement Deficiency) Neisseria C1 Esterase Deficiency Angioedema
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