Hyponatremia – 9/18/18

Thanks to Joe for presenting the case of a young man with no known medical history who presented with acute onset of generalized weakness, found to have symptomatic hyponatremia to 120 resulting from psychogenic polydipsia!

Clinical Pearls

  • Hyponatremia is largely a problem of too much free water (sometimes compounded by too little solute) and defined as a Na <135
  • Pick a systematic approach to solving the underlying diagnosis for any patient with hyponatremia (see below for one possible outline).
  • The term “pseudohyponatremia” refers to the presence of substances that interfere with laboratory measurement of sodium concentration in the blood, specifically high triglycerides and paraproteins.
    • Hyperglycemia does NOT fall into this category because glucose is osmotically active and pulls water into the intravascular space, resulting in a dilutional and true hyponatremia.
  • Chronic hyponatremia (>72 hours) must be corrected slowly to avoid osmotic demyelinating syndrome (ODS).  Acute hyponatremia (<48 hours) can be corrected more rapidly.  That said, we rarely have a Na value within 48 hours prior to patient presentation to determine acuity.  As a result, and given the neurologic risks, most patients are treated as if they have chronic hyponatremia.
  • ADH leads to increased uric acid excretion through the kidneys so low serum uric acid levels have been associated with SIADH.  But this test is not very specific.
  • Osmolarity of normal saline is 308 compared to human serum which is normally 280-295.  In a hyponatremic patient, NS infusion becomes a relatively hypertonic (rather than isotonic) solution!


For more detailed information, refer to this prior post and this review article.

Metformin Associated Lactic Acidosis (MALA) 9/17/2018

Thanks to doctor-in-training Emma who presented a case of an elderly woman, on dialysis, who came in with SEVERE lactic acidosis due to a variety of factors, but largely contributed by being prescribed metformin 2 weeks prior to presentation.

We will use this case to illustrate several concepts:

On initial presentation, pt was in a state of shock. If you remember from medical school, there are mainly 4 types:

  • Cardiogenic
    • Myopathic (DCM, acute MI)
    • Mechanical (Acute MR, VSD, severe AS)
    • Arrhythmia
  • Hypovolemic
    • Hemorrhage, volume depletion
  • Distributive
    • Sepsis
    • Anaphylaxis
    • Neurogenic (spinal cord injury)
    • Endocrine (myxedema, Addison’s)
  • Obstructive
    • Pericardial tamponade
    • PE
    • Pneumothorax

Shock can also be approached from a cardiac output standpoint to help differentiate the potential causes:


If someone is hypovolemic, but he/she is found to be hypotensive but bradycardic (instead of tachycardic), remember from physiology:

MAP = CO x SVR, where CO is cardiac output, SVR is systemic vascular resistance

CO = SV x HR, SV is stroke volume, and HR is heart rate.

Hence in a state of hypovolemia, the body will attempt to maximize CO by increasing HR to maintain adequate MAP. If you see the opposite though, there could be something else going on…

  • Cardiac: MI, conduction abnormalities, infectious (Lyme, Charga’s)
  • Toxic/Meds: CCB, Beta blocker, Dig, Alpha 2, organophosphate
  • Lytes: Hyperkalemia -> heart block -> sinus arrest
  • Endocrine: Hypothyroidism (myxema coma), adrenal insufficiency
  • Environmental: Hypothermia
  • Neurogenic shock


Acid-Base: Acid-base disorders can appear daunting, but the following algorithm can make things simpler if followed consistently. We will work through this patient’s acid/base disorder together. Her HCO3 is 6, AG of 52, with an ABG of 6.83/13/170.

  1. Look at the pH: < 7.4 automatically means some sort of acidosis is going on.
  2. Next look at the PCO2, if it is in the same direction as the pH (low PCO2 in this case, and low pH), then it is suggestive of a primary metabolic rather than a respiratory issue causing the acidosis. If pH is low and PCO2 is high, then there is high suspicions for a respiratory process driving the acidosis.
  3. Look at the Anion Gap, which in this case in 52. Go through your differential for AGMA.
  4. Calculate the Delta Gap. This basically is a way to assess whether a mix acid/base disorder exists after taking into account the AG. To help illustrate:Capture2
  5. Delta gap = calculated AG – normal AG = 52 – 12 = 40. Now there are several ways to do this, but one method that’s quick and simple is to simply add this delta gap to the measured bicarb and see what other metabolic acid/base disorders can be hiding beneath the anion gap. In this case, 40 + 6 = 46, which is suggestive of an underlying metabolic alkalosis.
  6. Lastly, calculate compensation. For AGMA, use Winter’s Formula = 1.5 (HCO3) + 8 +/-2. The calculated PCO2 should be 15-19. Since our measured PCO2 is 13, which is lower than expected, then this is suggestive of an underlying respiratory alkalosis as well, probably due to sepsis.
  7. Our final answer for the acid/base disorder for this patient is: AGMA with metabolic alkalosis and concurrent respiratory alkalosis!


Lactic Acidosis: Traditionally we view this as a sign of sepsis, or a marker of tissue hypoperfusion. However this is not always the case!

  • Type A: Inadequate oxygen delivery
    • Rule of thumb: Tissue hypoperfusion, tissue ischemia
    • Can also be seen with increased anaerobic muscular activity, like generalized convulsions in a seizure
    • Can also be seen in hypoxemia, severe anemia
    • Cryptic shock (elevated lactate, okay BP), similar to overt septic shock in terms of mortality in setting of severe sepsis.
  • Type B: altered physiology, others
    • B1: Underlying disease, malignancy, hepatic & renal failure
    • B2: Drugs, toxins
    • B3: Inborn errors of metabolism, enzyme deficiency
  • Management: Tx the underlying cause, bicarb controversial, studies have shown no benefits? But most experts would agree with usage in critically ill patients with profound acidemia.


MALA: Lastly, this case illustrates the dangers of metformin, in the right setting, can lead to severe acid/base disturbance (MALA).

  • Do NOT use metformin if GFR < 30, be careful in CKD patients.
  • If suspecting metformin toxicity and pt is hyperglycemic, this is a sign of severe toxicity.
  • Always do a thorough med reconciliation on every single patient!

Aplastic Anemia 9/12/2018

Today our Doctor-in -Training, Emma, presented a case of a middle age woman with no significant medical or family history coming in with a month of fatigue, menorrhagia, and gum bleeding. She was incidentally found to be pan-cytopenic. Bone marrow biopsy revealed hypocellularity with no abnormal morphologies, which is consistent with aplastic anemia!

Aplastic anemia

  • Epidemiology
    • Rare, 2 per million per year, higher incidence amongst Asians, can occur in all ages but most of the time in the first 1st-4th decades.
  • Pathophysiology
    • Big picture: Think of it this way. Aplastic anemia is similar to a factory not working due to not enough workers (stem cells). Compare and contrast this with MDS, which is basically a loss of quality control (mutation in the stem cells) leading to bad products that get worse over time (leading eventually to pancytopenia, leukemia).Capture
      • Causes
        • Primary (rare), most of the time acquired
        • Infectious: CMV, Parvo, EBV, HIV, hepatitis, TB
        • Toxins: Benzene, glue vapors, solvents, pesticides
        • Autoimmune: SLE, eosinophilic fasciitis, graft v host,
        • Other: Pregnancy, paroxysmal nocturnal hemoglobinuria, thymoma, irradiation
        • Medications: NSAIDS, Bactrim, Lasix, Gold, Allopurinol, penicillamine, phenothiazines, AEDS, anti-psychotics
      • Association
        • PNH: CD55 & CD59 abnormalities can be sen in up to 50% of patients with aplastic anemia!
      • Presentation
        • S/S of anemia
        • S/S of thrombocytopenia (menorrhagia, petechiae)
        • Recurrent infections
      • Diagnosis
        • Bone marrow biopsy most definitive, helps distinguish AA from other causes of pancytopenia
        • BM finding
          • Hypocellular, marrow space mostly fat cells and marrow stroma.
          • Remaining cells are morphologically normal
          • No fibrosis, no e/o malignancy
        • Severe AA criteria
          • BM cellularity < 25 + 2 of ANC < 500, plt < 20k, retic < 20k
        • Very Severe AA criteria
          • ANC < 200
        • Mgx: Severe AA require treatment
          • Under age 20: Early allogeneic HCT as soon as possible. If HCT not possible, immunosuppressives
          • 20 – 50: HCT also recommended if no contraindications, immunosuppressives (Anti-thymocyte globulin, cyclosporine for example) + eltrombopag (thrombopoietin agonist) otherwise.
          • > 50:
            • Transplantable: Early hematopoietic cell transplantation
            • Older, not candidates for HCT: Immunosuppressive, less intense preferred as age increases.
          • Treat other underlying/reversible causes in all cases.

Fun Fact: Blood transfusion can lead to falsely elevated iron studies within the first 24-36 hours.

Angioedema 9/11/2018

Today Arthur presented a case of a young woman with a personal and family history of facial swelling presenting with acute onset periorbital and scalp swelling, in setting of recent hair-dye exposure. No urticaria or pruritus on presentation but she did have acute pruritus after exposure to the hair-dye. She responded quickly to benadryl and steroids. The final diagnosis is allergic angioedema.

What is angioedema? It is a non-pitting swelling of the deep/subcutaneous tissues.


(Image adapted to JAMA)

Pathophysiology of angioedema

  • Mast cell mediated (most common)
    • Examples: Food allergies, insect stings
    • IgE -> Mast Cells -> inflammatory response
      • BeE, FoodiE = IgE
    • Findings:
      • Flushing
      • Urticaria
      • Generalized pruritus
      • +/- bronchospasm, throat tightness, hypotension
    • Onset: Minutes after exposure, develop over the next few hours
    • Recovery: 24-48 hours
    • Anaphylaxis = life threatening systemic reaction which is a severe manifestation of an allergic reaction. Angioedema is a finding.
    • Management: IM Epi is FIRST LINE, 0.3 – 0.5mg IM, repeat Q5-15min PRN. Everything else (steroids, benadryl, anti-histamines) are adjuvant only. Get that IM Epi stat.
  • Bradykinin mediated
    • Examples: Acquired angioedema (AAE, associated with underlying malignancy or autoimmune conditions), RAAS-blocker angio edema (RAE, African Americans are 3x likely vs Whites), hereditary angioedema (HAE, autosomal dominant mode of inheritance)
    • Findings:
      • Absent urticaria/pruritus, bronchospasm.
      • Minimal skin findings but can have swelling without urticaria.
    • Onset: More prolonged course, can develop over 24-36 hours
    • Recovery: 2-4 days
    • Management: depends
  • Histamine/Unclear: Seen in idiopathic angioedema (IAE)

Angioedema algorithm


HAE Management

  • C1 Inh concentrate (takes a while to obtain)
  • Icatibant (synthetic bradykinin receptor antagonist)
  • Ecallantide (recombinant plasma kallikrein inhibitor)
  • FFP (fastest to get!)
  • Supportive care, airway monitoring

Still’s Disease – 9/10/18

Thanks to Becky Lee yet again for presenting an interesting case of a young woman presenting with acute onset of fever and polyarthritis, found to have a history of similar episodes in the past together with a rash concerning for Still’s disease!

Clinical Pearls

  • Still’s disease is a diagnosis of exclusion!  Yamaguchi criteria can help with ruling in the diagnosis.
  • Still’s remains a multi-systemic disorder of unknown etiology because it’s difficult to diagnose and rare (0.16 cases per 100,000).
  • RF and ANA are generally negative but can be positive in <10% of patients with Still’s in low titers.
  • ~66% of patients present with sore throat secondary to cricothyroid perichondritis or aseptic nonexudative pharyngitis.
  • The disease is often recurrent.  Predictors of poor outcome include erosive polyarthritis on presentation and shoulder/hip involvement.

Acute polyarthritis (>5 joints involved):

Remember that for rheumatologic disorders, timing, symmetry, and number of joints involved is crucial to coming up with a differential diagnosis.  So for our patient with acute polyarthritis, consider the following:

  • Infection
    • Viral: hepatitis, HIV, parvovirus B19
    • Spontaneous bacterial endocarditis
  • Rheumatologic:
    • Rheumatoid arthritis
    • Reactive arthritis
    • SLE
    • Dermatomyositis
  • Vasculitis
    • PAN
  • Drug reactions
  • Auto-inflammatory or disease of the innate immune system (as opposed to autoimmune or diseases of the adaptive immune system):
    • Periodic fever syndromes (TRAPS, PFAPA, hyper-IgD syndrome)
    • Still’s disease
  • Schnitzler’s syndrome – chronic urticaria associated with a monoclonal gammopathy (usually IgM kappa)
  • Sweet syndrome – painful skin lesions
  • Sarcoid
  • Kikuchi disease – cervical LAD and fever (necrotizing lymphadenitis)
  • HLH/Macrophage activation syndrome – leukopenia and thrombocytopenia, elevated triglycerides, low fibrinogen and haptoglobin

Still’s disease:

  • Some clarifications on nomenclature:
    • Systemic juvenile idiopathic arthritis (sJIA): first presentation <17 years old, previously referred to as Still’s disease
    • Adult onset Still’s disease (AOSD): first presentation  > 17 years old
  • Epidemiology of AOSD:
    • 0.16 cases per 100,000
    • No sex predominance (F=M)
    • Bimodal age distribution with peak between 15-25 and another 36-46 years of age.  New diagnosis in patients >60 have been reported.
  • Clinical features ⇒ Yamaguchi criteria (need 5 total with  > 2 major)
    • Major criteria:
      • Daily fevers to 39
      • Arthritis >2 weeks
      • Non-pruritic salmon-colored macular/maculopapular rash on trunk or extremities (though cases of pruritic rash have also been reported)
      • ↑ WBC >10k, >80% neutrophils
    • Minor
      • Sore throat
      • LAD and/or splenomegaly
      • ↑ AST, ALT, or LDH
      • Negative ANA/RF
  • Treatment
    • Mild: NSAIDs
    • Moderate: NSAIDs + DMARDs
    • Severe: NSAIDs + DMARDs (IL1 receptor antagonists like anakinra appear to be more helpful than TNF inhibitors especially in sJIA)
  • Prognosis:
    • Overall good prognosis
    • Disease can be limited to one episode or recurrent over time
    • Poor prognostic indicators:
      • Hip and shoulder involvement
      • Erosive polyarthritis at initial diagnosis
  • Complications
    • Macrophage activation syndrome (ie HLH) can occur in 15% of cases
    • DIC
    • TTP
    • Diffuse alveolar hemorrhage
    • Pulmonary HTN
    • Aseptic meningitis


Great recent review article on Still’s disease (AOSD Review) and this prior post on our blog!

Adrenal insufficiency, lupus flare, and mixed AIHA- 9/6/18

Thanks to Becky for presenting the case of a middle-aged woman with h/o SLE and Evans syndrome who presenting with subacute onset of fatigue after her prednisone dose was reduced, found to have iatrogenic adrenal insufficiency, lupus flare, and mixed autoimmune hemolytic anemia!

Clinical Pearls:

  • Evans syndrome describes AIHA + ITP, a rare condition associated with SLE and often precedes the diagnosis of SLE by a few years.
  • Hematologic manifestations of SLE are many and include the following
    • Anemia (chronic disease, iron deficiency, medication-induced, warm AIHA>>cold AIHA, pure red cell aplasia, MAHA, and pernicious anemia)
    • Leukopenia
    • Thrombocytopenia
    • Pancytopenia
    • Evans syndrome
  • Smear findings can be very helpful in diagnosing different types of hemolytic anemiasSchistocytes are a very specific for MAHA, valve disorders, AVMs, APLS whereas AIHA would result in spherocytes. 
    • The negative predictive value of spherocytes is low.  So a smear without spherocytes does not rule out AIHA!
  • Lastly, the most common cause of adrenal insufficiency (AI) is iatrogenic.
    • General rule of thumb for when risk of AI is high and you should taper steroids slowly is if someone is on prednisone > 20 mg for > 3 weeks.  Keep in mind that people with smaller BSA would be more susceptible to AI and at risk with even lower doses.

Hemolytic anemia work up

Check smear

  • Schistocytes
    • Valve disorder
    • AVMs
    • APLS
  • No schistocytes (+ spherocytes)
    • Intrinsic RBC defect
      • Enzyme deficiency (G6PD)
      • Hemoglobinopathy (sickle cell)
      • Membrane defect (hereditary spherocytosis)
    • Extrinsic RBC defect
      • Liver disease
      • Splenic sequestration
      • Infections (clostridium perfringens, babesia, malaria, bartonella)
      • Meds/toxins (dapsone, nitrites, lead, copper, snake venom)
      • AIHA (warm and cold)
    • Intravascular
      • Transfusion reaction
      • Infections
      • PNH

Lab findings in AIHA: 

  • ↑ retic
  • ↑ indirect bili
  • ↑ LDH
  • ↓ haptoglobin
  • + DAT (but keep in mind that DAT can be negative in 3% of patients with WAIHA)
  • + spherocytes

Summary of AIHAs:



Stress-induced cardiomyopathy – 9/5/18

Thanks to Eric for presenting the case of an “late middle-age” woman with chest pressure, found to have ST depressions, troponin elevation, TTE with apical akinesis, and clean coronaries on cardiac cath concerning for Takotsubo cardiomyopathy.

Clinical Pearls

  • Think of heart failure as ischemic vs non-ischemic
  • Most common causes of heart disease are ischemia (CAD), HTN, idiopathic, valvular, infectious (viral), and drugs.
  • MINOCA or myocardial infarction with nonobstructive coronary arteries is MI in the absence of coronary artery disease with >50% vessel occlusion and includes the following etiologies
    • Stress induced cariodmyopathy (Takotsubo)
    • Coronary vasospasm
    • Microvascular dysfunction
  • Takotsubo cardiomyopathy most commonly presents in postmenopausal women and triggered by physical or emotional stress.  The pathogenesis is not well understood and the course is self-limited.  Treatment is largely supportive.  Prognosis to recovery of cardiac function is 1-4 weeks.

Heart failure

  • Ischemic
    • CAD
    • Bridge
  • Non-ischemic
    • HTN
    • Valvular disease
    • Idiopathic
    • Infectious (viral is most common)
    • Infiltrative (sarcoid, amyloid, hemochromatosis)
    • Stress induced cardiomyopathy (Takotsubo)
    • Arrhythmia
    • High output (secondary to anemia, Paget’s disease, pregnancy, AV fistula, beriberi, hyperthyroidism)
    • Post-partum
    • Hypothyroidism
    • OSA
    • Connective tissue disease

MI with non-obstructive coronary arteries (MINOCA)

  • Diagnosis: requires the following
    • Clinical documentation of MI
    • Exclusion of obstructive CAD
    • No overt cause for acute MI present
  • Etiologies: significant overlap with non-ischemic causes of heart failure
    • Non-cardiac
      • Reduced troponin clearance (i.e. renal impairment)
      • Increased right heart pressures (ex PE)
    • Cardiac causes
      • Stress induced cardiomyopathy
      • Inflammation (myocarditis)
      • Coronary artery spasm (vasospastic angina)
      • Microvascular dysfunction (microvascular angina, microvascular spasm, coronary slow flow phenomenon)
      • Thrombophilia
  • Work up
    • MINOCA is a working diagnosis
      • Exclude non-cardiac cause
      • Rule out ischemic etiology
      • TTE
      • Cardiac MRI is often indicated
      • Provocative spasm testing (with acetylcholine etc in the case of coronary vasospasm)

Takotsubo cardiomyopathy

  • First described in Japan in 1990
  • It is the underlying etiology in ~1-2% of patients presenting with ACS
  • More common in post-menopausal women (mean age 66.4)
  • Pathogenesis:
    • Not well understood
  • Clinical manifestations
    • Often triggered by emotional or physical stress but ~30% of the time, no trigger is identified
    • Symptoms
      • Most commonly present with acute substernal chest pain.  Less commonly present with SOB or syncope or heart failure symptoms
    • Exam
      • May have late peaking systolic murmur similar to HOCM
    • EKG changes:
      • ST elevation in anterior leads (43.7%)
      • ST depression (7.7%)
      • QT prolongation, T wave inversion, abnormal Q waves
    • Troponin elevation in most patients (mean initial troponin is ~7-8)
    • Diagnostic criteria
      • Transient LV systolic dysfunction (hypokinesis, akinesis, or dyskinesis), wall motion abnormalities that extend beyond a single epicardial coronary distribution
      • Absence of CAD based on cath
      • New EKG abnormalities
      • Absence of pheochromocytoma or myocarditis
    • Work up
      • Rule out ACS
      • Cardiac MRI to rule out other causes of MINOCA
    • Management
      • Supportive
    • Prognosis
      • Recovery in 1 to 4 weeks


Picture above and cool video from NEJM here.