Pop Quiz: Mind the (protein) Gap

Below you will find a brief pop quiz in follow up to Dr Doan's wonderful case of Multiple Myeloma presenting as profound AKI (Cr 8!).

1) What two labs do you need to identify a protein gap?

2) Name two infectious causes of an elevated protein gap?

3) What is the most common presenting symptom of the CRAB criteria?

4) What are the two "magic numbers" for abnormal values of the CRAB criteria?

5) What is the "money" finding of multiple myeloma on peripheral smear?

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ANSWERS:

1) serum protein - serum albumin = protein gap 2) HIV, Hep C 3) Bone Pain (CRAB is written in least to most common order of symptoms: #1 bone pain, #2 renal failure, #3 anemia, #4 hypercalcemia) 4) 10 and 2! (Ca > 10.2, Hg < 10, sCr >2) 5) Rouleax Formation (French for "cylindrical roll of coins")

How'd you do?

Idiopathic Interstitial Pneumonia

Thank you to Dr. Burnett who presented a complex pulmonary case in Intern Report today. The case allows for a refresher on idiopathic interstitial pneumonias and BAL results.

Idiopathic insterstitial pneumonias are a subset of diffuse instersitial lung disease with an inflammatory infiltrate in the interstitial compartment occasionally accompanied by fibrosis. Interstitial pneumonia can be idiopathic or associated with other conditions such as connective tissue disease, HIV, drugs or hypersensitivity. Idiopathic interstitial pneumonias include: idiopathic pulmonary fibrosis, idiopathic nonspecific insterstitial pneumonia (NSIP), respiratory bronchiolitis-interstitial lung disease, desquamative instersitial pnuemonia, cryptogenic organizing pneumonia and acute interstitial pneumonia (AIP). Interestingly, AIP is rapidly progressive and histologically indistinguishable from ARDS. Diagnosis can be aided by imaging such as CXR and HRCT. For information on the radiographic and pathologic findings, please refer to the article in Current Problems in Diagnostic Radiology. It is also useful to compare prior imaging to assess for rate of change. In this case, a BAL was also performed. And with a negative infectious and rheumatologic evaluation, the patient was diagnosed with idiopathic interstitial pneumonia and treated successfully with steroids.

 American Thoracic Society guidelines on BAL interpretation in interstitial lung disease

American Thoracic Society guidelines on BAL interpretation in interstitial lung disease

Tracheobronchomalacia

Dr. Thapa presented an interesting case for intern report of an older female with a complicated history of pulmonary and cardiac sarcoidosis, chronic systolic HF, and OSA on CPAP who presented with subacute progressive dyspnea on exertion and cough, initially admitted with concern for acute decompensated heart failure. She continued to have DOE and cough despite adequate diuresis and a RHC showing euvolemia. Eventually, she was diagnosed with tracheobronchomalacia on dynamic CT chest imaging.

 Image from:&nbsp;http://curetbm.org/about-tbm.html

Image from: http://curetbm.org/about-tbm.html

Learning Points:

Tracheobronchomalacia can be congenital or acquired. Factors associated with its development include endotracheal intubation (worse with recurrent intubation, prolonged intubation, concurrent steroid therapy), cartilage injury, chronic compression, relapsing polychondritis, recurrent infection (chronic bronchitis, CF), severe emphysema/smoking, mustard gas, and GERD.

Diagnosis can be made with dynamic CT chest imaging, but gold standard remains direct visualization of airway collapse on bronchoscopy. PFTs are not diagnostic and have variable patterns (obstructive, restrictive, mixed, normal).

Treatment includes optimizing the underlying issue, performing functional assessments, and inserting a trial of silicone stents. If helpful symptomatically and the patient is a surgical candidate, definitive surgical repair can be considered.

MTX Pneumonitis

Thank you to Dr. Wendy Reeve for an interesting case of acute hypoxemic respiratory failure secondary to methotrexate pneumonitis.

Remember that methotrexate is a folic acid analog that inhibits cellular proliferation through intracellular depletion of folate requiring coenzymes. It can have a variety of toxicities and side effects which include everything from mild GI upset to fever, hepatotoxicity, nephrotoxicity, pulmonary toxicity, myelosuppression and increased risk of infections and lymphoproliferative disorders.

Methotrexate pneumonitis is more likely in individuals over 60 years old, those with RA and pleuropulmonary disease, those on DMARDs, those with low albumin and diabetes.The diagnosis of methotrexate pneumonitis is made with the aide of hte Searles and Mckendry criteria:

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Please reference the article associated with the above table to learn more about how to reduce the risk of MTX pneumonitis. And, for additional reading, please see the 2014 meta-analysis of MTX and lung disease in RA patients.

Chest Pain + Bezold-Jarisch Reflex

Thanks to Dr. Levin today for her case of chest pain which reminded us of coronary anatomy distribution on ECGs and post-MI complications. It also highlighted the importance of good sign-out during transitions of care.

 Image adopted from  ecgwaves.com  for reference.&nbsp;

Image adopted from ecgwaves.com for reference. 

Remember to correlate the ST changes on the ECG to the myocardial territory and the coronary anatomy. This will help you think through complications and what other tests may be useful (i.e. posterior or right sided ECG).

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One complication of myocardial ischemia is arrhythmia. Many may recall that the SA node is supplied by the RCA (60%) or LCX (40%) and, the AV node is supply by the RCA (90%) or LCX (10%). Thus, RCA infarcts can lead to bradycardia via loss of blood supply to those regions. However, another physiologic response called the Bezold-Jarisch Reflex (BJR) is another explanation for arrhythmias. The BJR plausits that myocardial ischemia results in hypotension and bradycardia via stimulation of the cardioinhbitory C fiber afferent receptors in the myocardium. The greatest concentration of these fibers are in the inferior and posterior wall of the heart which just so happen to be supplied by the RCA and LCX. This reflux was thought to be the result of the transient bradycardia and hypotension in this patient who had a distal RCA occlusion on coronary angiogram. For more information of the BJR take a look at this review article in Anesthesiology from 2003.

For additional review on chest pain and CAD diagnosis, evaluation and treatment, please see Dr. Lesselroth's handy pocket cards.

Unintentional Weight Loss

Dr. Steven Koprowski presented a case of an older gentleman with cirrhosis, hemochromatosis, osteoporosis with compression fractures and recent admission for 100 lb unintentional weight loss who presented with acute onset dyspnea and hypoxia in the setting of somnolence with escalating opiate doses. He was ultimately diagnosed with a multifocal aspiration PNA. In addition, work up revealed an extremely elevated TTG with biopsy proven celiac disease as the etiology of his unintentional weight loss.

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Learning Points:

Clinically significant weight loss is >5% of usual body weight over 6-12 months.

The DDx is expansive, thus a careful history and physical exam can help guide your diagnostic testing. It is important to document amount and pattern of weight loss, associated symptoms (GI symptoms, malabsorption, malignancy signs and symptoms, psych), med list, and functional factors (dysphagia, poor dentition, cognitive issues).

The major causes of unintentional weight loss include:

  • Malignancy (GI, lung, lymphoma, renal, prostate cancers)
  • GI diseases (IBD, peptic ulcer disease, celiac disease)
  • Psychiatric disorders
  • Endocrinopathies
  • Infectious diseases (HIV, TB, viral hepatitis, chronic fungal, bacterial or parasitic infections)
  • Advanced chronic disease (heart failure, COPD, renal failure)
  • Neurologic diseases (CVA, dementia, ALS)
  • Medications/substances (alcohol, cocaine, amphetamines, tobacco, herbals)
  • Rheumatologic diseases (RA, vasculitis)

Diagnostic testing is often based on history and physical and can include CBC with diff, CMP, hemoglobin A1c, calcium, UA, TSH, ESR/CRP, HIV, hep C, CXR, and age appropriate cancer screening. Advanced diagnostics (i.e. EGD, colonoscopy, CT imaging is often guided by clinical suspicion).

Statin-Induced Autoimmune Myositis

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Today Dr. Peng presented a case of immune-mediated necrotizing myopathy in association with statin therapy which presented with dysphagia for several weeks and a profound CK elevation.

On review, there appears to be a range of statin associated myopathies. Some of these appear to improve with discontinuation of the statin itself. These are likely a result of the direct toxic effect of that statin on muscle tissue. However, others do not improve and follow a pattern more typically seen with immune-mediated necrotizing myopathies which include anti-SRP and paraneoplastic necrotizing myositis. The illness script here includes CK greater than 3k and rapid onset of weakness and/or dysphagia from severe myopathy. There is also and argument to that criteria for dermatomyositis and polymyositis should also be included in this description and would include symmetrical, proximal muscle weakness. However, in statin-induced autoimmune myositis thre is limited or absent inflammation on muscle biopsy. In these individuals, the anti-HMGCoA reductase autoantibody is elevated. This is a rare form of nectrotizing myositis which often requires immunosuppression to alleviate symptoms. Please see the article in Autoimmune Review for more information on statin-induced autoimmune myositis. Some other important considerations are to evaluate for hypothyroidism and vitamin D deficiency as these increase the susceptibility of the individual. Additionally, recommendations are to assess for drug-drug interactions (remember the CYP3A4 enzymes!).

Rhabdomyolysis

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Dr. Kiefer presented a case of rhabdomyolysis today likely multifactorial with a major contribution from drug-drug interactions and increased exertion. It reminded us of the extensive differential for rhabdo and that we need to be on the look out for associated complications.

Rhabodomyolysis is essentially muscle necrosis with the release of intracellular muscle constituents such as creatinine kinase (CK). It can range from asymptomatic elevations in CK to life threatening with severe electrolyte abnormalities and AKI. The classic symptom triad is muscle pain, weakness and dark urine (myoglobinuria).

The causes of rhabdomyolysis can be thought of in three broad categories encompassing an enormous number of etiologies:

  • Traumatic: trauma, crush injuries, surgery, coma, immbolization, electric voltage
  • Nontraumatic, Exertional: extreme exertion (marathon running, cross fit), environmental heat illness, seizures, hyperkinetic states (psychotic agitation, amphetamine OD), metabolic or mitochondrial myopathies, malignant hyperthermia, neuroleptic malignant syndrome
  • Nontraumatic, Nonexertional: alcoholism, drugs (heroin, cocaine, amphetamines, methadone, LSD, statins, colchicine, dietary supplements), toxins (snake or insect venom, mushrooms, fish toxin), infections (influenza A/B, coxsackie, EBV, HSV, parainfluenza, adenovirus, echovirus, HIV, CMV, mycoplasma pneumoniae, bacterial myositis, legionella, tularemia, strep, salmonella, leptospirosis, coxiella burnetti, erclichiosis, malaria), electrolyte abnormalities, endocrinopathies (hyothyroidism, DKA, HHS, pheochromocytoma), inflammatory myopathies, status asthmaticus, capillary leak syndrome, abrupt withdrawl of GABA agonist (ex. intrathecal baclofen)

As you continue to asssess your patient, it is important to monitor for complications and associated symptoms which can include:

  • hypovolemia with third spacing
  • electrolyte derrangements: potassium, phosphate, calcium, uric acid (check and EKG and consider telemetry)
  • metabolic acidosis
  • AKI (monitor UOP and need for dialysis)
  • compartment syndrome
  • DIC (assess for bleeding)

Remember that management is driven by prevention and addressing hte underlying etiology.

  • address hypovolemia and utilize volume to "wash out" obstructing pigment casts in the kidney: 500ml/hr x24 hours and then goal UOP 200-300ml/hr
  • electrolyte managment: assess potassium and monitor for arrythmias