Hypocalcemia

Brief H&P:

34M with a history of HTN, polysubstance abuse, presenting with muscle cramps. He reported onset of diffuse muscle cramping 1-hour prior to presentation while showering. Symptoms involved bilateral upper and lower extremities and resolved spontaneously.

On initial evaluation, the patient was tachycardic and hypertensive. Examination was notable for tremors in bilateral upper extremities with outstretched hands, as well as of extended tongue. Other notable findings included spasm of the upper extremity during blood pressure measurement, hyperreflexia and clonus.

Laboratory evaluation was notable for normal total calcium level, low ionized calcium level, primary respiratory alkalosis, and elevated anion gap metabolic acidosis.

The patient was treated with intravenous fluids, benzodiazepines for alcohol withdrawal, and calcium gluconate 4g IV and was admitted.

Calcium Homeostasis1

  • Fraction
    • 15% bound to anions (phosphate, lactate, citrate)
    • 40% bound to albumin
    • 45% free (regulated by PTH, Vit-D)
  • Conditions causing changes in total calcium (without affecting ionized calcium)
    • Low albumin causes hypocalcemia. Corrected = measured + [0.8 x (4-albumin)]
    • Elevated albumin causes hypercalcemia
    • Multiple myeloma causes hypercalcemia
  • Conditions causing changes in ionized calcium (without affecting total calcium)
    • Alkalemia causes increased ionized calcium binding to albumin and decreases ionized calcium levels
    • Hyperphosphatemia causes increased ionized calcium binding to phosphate and decreases ionized calcium levels
    • Hyperparathyroidism causes decreased ionized calcium binding to albumin and increases ionized calcium levels

Causes of Hypocalcemia1,2,3

Algorithm for the Evaluation of Hypocalcemia

Symptoms1

Acute Chronic

Neuromuscular

  • Paresthesia
  • Tetany
  • Carpopedal spasm
  • Trousseau
  • Chvostek
  • Seizure
  • Laryngospasm

Cardiac

  • QT prolongation
  • Hypotension
  • Heart failure
  • Arrhythmia

CNS

  • Basal ganglia calcifications
  • EPS
  • Parkinsonism
  • Dementia

Ophthalmologic

  • Cataracts

Management

  • Severe (symptomatic, QT prolongation)
    • Calcium gluconate 1-2g IV in 50mL of D5W over 10-20min followed by slow infusion of additional 2g over 2 hours.
  • Asymptomatic
    • Calcium gluconate 1g PO q6h
    • Calcitriol 0.2mcg PO BID

References:

  1. Yu, AS. Relation between total and ionized serum calcium concentrations. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on October 6th, 2016.)
  2. Cooper MS, Gittoes NJL. Diagnosis and management of hypocalcaemia. BMJ. 2008;336(7656):1298-1302. doi:10.1136/bmj.39582.589433.BE.
  3. Hannan FM, Thakker RV. Investigating hypocalcaemia. BMJ. 2013;346(may09 1):f2213-f2213. doi:10.1136/bmj.f2213.

Bleeding Disorders

Overview

  • Disorders of primary hemostasis
    • General: present with mucocutaneous, post-operative bleeding
    • vWD
    • Platelet disorders
      • Medication-induced: NSAID, valproate, B-lactam, SSRI
      • Systemic disease: hepatic, renal failure
    • ITP: antibody-mediated platelet destruction
  • Disorders of secondary hemostasis
    • General: present with bleeding into soft-tissue, joints
    • Hemophilia A (VIII)
    • Hemophilia B (IX)
  • Disorders of both primary and secondary hemostasis
    • DIC
    • Liver disease
    • Severe vWD
  • Evaluation
    • PT: VII, vitamin K
    • PTT: VIII, IX, XI, XIII, vWD, heparin
    • Increased PT/PTT: XI, V, vitamin K, heparin, DIC
    • CBC: degree of anemia, platelet count, differential (hematopoetic disorders)
  • Management
    • Thrombocytopenia
      • Prophylactic transfusion for avoidance of spontaneous hemorrhage for platelet count <10,000
      • Transfusion for active bleeding at platelet count <50,000
      • Dosing
        • Adults: one RDP increases platelet count by 7-10,000
        • Pediatrics: 5-10ml/kg
      • ITP
        • Transfuse platelets for active bleeding
        • High-dose steroids (prednisone 1mg/kg)
        • IVIG (1g/kg/d)
      • Uremia
        • Hemodialysis
        • DDAVP (0.3ug/kg IV)
      • vWD
        • DDAVP (0.3ug/kg IV)
        • Severe: VWF (Humate-P) 40-80IU/kg
        • Tranexamic acid
      • Hemophilia A
        • Minor: 20IU/kg
        • Major: 50IU/kg
      • Hemophilia B
        • Minor: 40IU/kg
        • Major: 100IU/kg

DIC/TTP/HUS

  • Disseminated Intravascular Coagulation
    • Etiology: severe systemic illness/injury
      • Trauma, burn, crush
      • Sepsis
      • Malignancy
      • Obstetric complication: abruption, amniotic fluid embolism
      • Hemolytic anemia
    • Exam: petechiae/purpura, hemorrhage (puncture site, GI, GU, pulmonary)
    • Labs:
      • PT/PTT
      • Fibrinogen
      • CBC: schistocytes, thrombocytopenia
      • FDP/D-Dimer
    • Management
      • Treat underlying illness
      • Transfuse (PRBC, FFP for INR > 2, cryoprecipitate for fibrinogen < 100)
      • Heparin if apparent embolic events
      • Consult hematology
  • TTP/HUS
    • Presentation
      • Thrombocytopenia
      • Altered mental status
      • Renal dysfunction
      • Fever
      • MAHA
    • TTP: more commonly associated with altered mental status
      • Etiology: drugs, pregnancy, infection (HIV)
      • Mechanism: ULvWF uncleaved by dysfunctional ADAMTS-13
    • HUS: more commonly associated with renal dysfunction
      • Mechanism: toxin from E. coli, Shigella
      • Timing: 1-2wks after diarrheal illness
    • Evaluation
      • CBC: anemia, schistocytes, thrombocytopenia
      • PT/PTT (normal)
      • BUN/Creatinine
      • LDH
    • Management
      • Platelets contraindicated except as stopgap measure in ICH (can worsen process)
      • Plasma exchange with FFP (replaces functional ADAMTS-13)
      • Steroids (prednisone 1mg/kg daily)
      • Hematology consultation

Complications of anti-thrombotic therapy

  • Agents
    • Anti-platelet
      • TXA: Aspirin
      • ADP: clopidogrel, ticagrelor, prasugrel
      • GPIIb/IIIa: abciximab, eptifibatide, tirofiban
    • Anti-coagulants
      • Anti-thrombin: heparin, LMWH (enoxaparin, dalteparin)
      • Vitamin K antagonist: warfarn (anti-II, VII, IX, X)
      • Direct thrombin inhibitor: bivalirudin, argatroban, dabigatran
      • Xa inhibitor: rivaroxaban, apixaban
    • Fibrinolytics
      • Alteplase, tenectaplase
  • Complications
    • HIT: platelet count decrease >50% at 5 days

Summary of Management

Agent Reversal
Aspirin, clopidogrel 5-10U platelets

DDAVP 0.3ug/kg

GPIIb/IIIa Abciximab: 5-10U platelets

Eptifibatide/tirofiban: none

Heparin Protamine 1mg/100mg heparin in last 2-3 hours
LMWH Enoxaparin: 1mg/1mg

Dalteparin: 1mg/100U

Warfarin See supratherapeutic INR algorithm
DTI Dabigatran: Praxbind, hemodialysis, consider Factor VIIa
Xa PCC
Fibrinolytics 10U cryoprecipitate, 2U FFP, consider platelets and aminocaproic acid (4-5g IV)

Oncologic Emergencies

Overview

  •  Complications
    • Airway obstruction
    • PNA
    • Pleural effusion
    • Pericardial effusion
    • VTE
    • SVC syndrome
      • Symptoms: dyspnea (airway edema), chest fullness, blurred vision, headache (increased ICP)
    • Massive hemoptysis
      • Management: ETT (large-bore for bronschoscopy), affected side down
  • Brain Metastases
    • Cancers: melanoma, lung, breast, colorectal
    • Management: dexamethasone 10mg IV load, elevated HOB, hypertonic saline or mannitol, prophylactic anti-eplipetics
  • Meningitis
    • Pathogens: Listeria (ampicillin), Cryptococcus (amphotericin)
    • Evaluation: CSF sampling with cytology (diagnose leptomeningeal metastases)

Metabolic Disturbances

  • Hypercalcemia
    • Cancers: MM, RCC, lymphoma, bone metastases (breast, lung, prostate)
    • Mechanism: metastatic destruction, PTH-RP, tumor calcitriol
    • Prognosis: 50% 30-day mortality
    • Symptoms
      • Chronic: anorexia, nausea/vomiting, constipation, fatigue, memory loss
      • Acute: CNS (lethargy, somnolence)
    • Findings
      • Calcium: >13.0mg/dL
      • ECG: QT shortening
    • Treatment
      • Mild: IVF
      • Severe: IVF, loop diuretics, bisophosphanate (pamidronate 90mg IV infused over 4 hours), consider calcitriol, consider hemodialysis if cannot tolerate fluids or unlikely to respond to diuretics
  • Hyponatremia
    • Cancers: lung (small-cell), pancreatic, ovarian, lymphoma, thymoma, CNS
    • Mechanism: SIADH
    • Symptoms: muscle twitching, seizure, coma
    • Management: fluid restriction, if seizing administer 3% hypertonic saline at 100cc/hr until resolution
  • Hypernatremia
    • Mechanism: decreased intake, increased GI losses from chemotherapy
    • Management: cautious fluid resuscitation
  • Tumor Lysis Syndrome (TLS)
    • Cancers: hematologic, rapid-growth solid tumors
    • Mechanism: release of intracellular contents (uric acid, K, PO4, Ca)
    • Timing: 1-4 days after therapy (chemo, radiation)
    • Diagnosis
      • Uric acid >8mg/dL
      • Potassium >6mEq/L
      • Calcium <7mg/dL
      • PO4 >4.5mg/dL
      • Acute kidney injury
    • Management
      • IVF, allopurinol, rasburicase, urinary alkalinization
      • Consider hemodialysis if volume overloaded

Localized Complications

  • Musculoskeletal Complications
    • Spinal cord compression
      • Cancers: prostate, breast, lung, RCC, non-Hodgkin lymphoma, MM (5-10% of all cancer patients)
      • Sites: thoracic (60%), lumbosacral (30%), cervical (10%)
      • Symptoms: pain (worse lying flat, cough/sneeze, heavy lifting)
      • Evaluation: MRI (se 93%, sp 97%)
      • Management: dexamethasone 10mg IV load, 4mg q6h, neurosurgical consultation, radiation oncology consultation
    • Pathologic fracture
      • Features: sudden onset, low-force mechanism
  • Therapy Complications
    • Neutropenic fever
      • Definition: ANC <500 or ANC <1000 with expected nadir <500 (nadir typically occurs 5-10d after chemotherapy) with Tmax >38.3°C or >38.0°C for >1h
      • Examination: subtle signs of infection, thorough examination is critical (skin, catheter, perineum)
      • Treatment: carbapenem monotherapy, vancomycin if indwelling catheter, oncology consultation for colony stimulating factors
    • Chemotherapy-induced vomiting
      • Management: ondansetron with dexamethasone, consider NK-1 antagonist (aprepitant)

Hematologic Malignancies

  • Acute leukemia
    • Signs/Symptoms: leukopenia (infection), anemia (weakness/fatigue), thrombocytopenia (bleeding)
    • Diagnosis: >5% blasts
  • Thrombocytopenia
    • Management
      • No bleeding, goal >10,000
      • Fever, coagulopathy, hyperleukoctosis, goal >20,000
      • One unit of platelets increases count by 5,000
  • Hyperleukocytosis
    • Definition: WBC > 50-100k
    • Complications: microvascular congestion (pulmonary, cerebral, coronary)
    • Symptoms
      • CNS: confusion, somnolence, coma
      • Pulmonary: dyspnea, respiratory alkalosis
    • Management: cytoreduction (induction chemotherapy, increased risk TLS)
  • Hyperviscosity
    • Cancer: macroglobulinemia, MM
    • Symptoms: epistaxis, purpura, GIB, neuro deficits
    • Diagnosis: serum viscosity > 1.4-1.8
    • Management: emergent plasmapheresis
  • Polycythemia
    • Diagnosis: Hb >17
    • Differential: dehydration, hypoxia, smoking, altitude
    • Symptoms: HA, vertigo, angina, claudication, pruritus (after showering)
    • Complications: thrombosis (stroke), bleeding
    • Management: emergent phlebotomy (500cc if otherwise healthy)
  • Thrombocytosis
    • Diagnosis: platelet >1,000,000
    • Symptoms: vasomotor (HA, lightheadedness, syncope, chest pain, paresthesias)
    • Management: low-dose aspirin

Acid-Base Disturbances

Method

  • Primary disturbance (acidemia/alkalemia)
  • Primary process (metabolic/respiratory)
  • Presence of mixed disorder
    • Increase PCO2 of 10, increases HCO3 by 1 (acute) or 3 (chronic)
    • Decreased PCO2 of 10, decreases HCO3 by 2 (acute) or 5 (chronic)
    • Increase HCO3 of 1, increases PCO2 by 0.7
    • Decreased HCO3, add 15, result should equal PCO2 and number after decimal of pH
  • Anion gap

Causes

  • Anion Gap
    • Methanol
    • Uremia
    • DKA/AKA
    • Paraldehyde, propylene glycol
    • INH
    • Lactate
    • Ethylene glycol
    • Salicylate
  • Non-Anion Gap
    • Fistulae
    • Ureteral fistulae
    • Saline
    • Diarrhea
    • Carbonic anhydrase inhibitors
    • Spironolactone
    • RTA
  • Metabolic Alkalosis
    • Vomiting
    • Volume depletion
    • Diuretics
    • Steroids
  • Respiratory Acidosis
    • CNS lesion
    • Myopathies
    • Chest wall abnormalities
    • Obstructive lung disease
  • Respiratory Alkalosis
    • Anxiety
    • Fever
    • Hyperthyroidism
    • Hypoxia
    • Sympathomimetic

See Also

Electrolyte Abnormalities

Routine laboratory studies are common in the intensive care unit; abnormalities are even more common. Typically these studies include a chemistry panel (Chem 10). The differential diagnoses of the most frequent and clinically relevant electrolyte abnormalities are detailed below.

Differential Diagnosis and Evaluation of Hyponatremia

Differential Diagnosis and Evaluation of Hyponatremia

Differential Diagnosis and Evaluation of Hypernatremia

Differential Diagnosis and Evaluation of Hypernatremia

Differential Diagnosis and Evaluation of Hypokalemia

Differential Diagnosis and Evaluation of Hypokalemia

Differential Diagnosis of Hyperkalemia

Differential Diagnosis of Hyperkalemia

Differential Diagnosis of Hypo and Hypercalcemia

Differential Diagnosis of Hypo and Hypercalcemia

Differential Diagnosis of Hypo and Hypermagnesemia

Differential diagnosis of hypo and hypermagnesemia

Differential Diagnosis of Hypo and Hyperphosphatemia

Differential diagnosis of hypo and hyperphosphatemia

References:

  1. Marino, P. (2014). Marino’s the ICU book. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins.
  2. Fulop, M. (1998). Algorithms for diagnosing some electrolyte disorders. American Journal of Emergency Medicine, 16(1), 76–84.
  3. WikEM: Hypokalemia
  4. WikEM: Hyponatremia

Hyponatremia

HPI:

62M with a history of hepatitis C cirrhosis complicated by hepatocellular carcinoma s/p radiofrequency ablation presenting after referral from hepatology clinic for hyponatremia. One week ago, the patient developed abdominal distension and shortness of breath that resolved after large-volume paracentesis and was started on furosemide 40mg p.o. daily and aldactone 100mg p.o. daily.

After initiating diuretics, the patient noted worsening lower extremity edema, and increased thirst/fluid intake.

He reports two days of fatigue and intermittent confusion supported by family members who reported slowed speech. He otherwise denies abdominal pain, distension, nausea/vomiting, diarrhea/constipation, chest pain or shortness of breath. In the ED, the patient received 1L NS bolus.

PMH:

  • Hepatitis C cirrhosis c/b HCC s/p RFA
  • Rheumatoid arthritis, well-controlled without medications

PSH:

  • None

FH:

  • Non-contributory.

SHx:

  • Lives with partner, denies current or prior t/e/d abuse
  • HepC contracted from blood transfusions

Meds:

  • Furosemide 40mg p.o. daily
  • Spironolactone 100mg p.o. daily
  • Rifaximin 550mg p.o. b.i.d.

Allergies:

NKDA

Physical Exam:

VS: T 98.2 HR 80 RR 14 BP 95/70 O2 98% RA
Vent: PRVC, VT 320, RR 35, PEEP 6, FiO2 95%
Gen: Elderly female in no acute distress, alert and answering questions appropriately.
HEENT: NC/AT, PERRL, EOMI, no scleral icterus, MMM.
CV: RRR, normal S1/S2, no murmurs. JVP 8cm.
Lungs: Faint basilar crackles on bilateral lung bases.
Abd: Normoactive bowel sounds, non-distended, non-tender, without rebound/guarding.
Ext: 2+ pitting edema in lower extremities to knees bilaterally. 2+ peripheral pulses, warm and well perfused.
Neuro: AAOx3. CN II-XII intact. No asterixis. Normal gait. Normal FTN/RAM.

Labs/Studies:

  • BMP (admission): 112/5.6/88/22/28/1.1/97
  • BMP (+10h): 118/5.4/93/23/26/1.0/133
  • sOsm: 264
  • Urine: Na <20, K 26, Osm 453
  • BNP: 40
  • AST/ALT/AP/TB/Alb: 74/57/91/2.4/2.2

Assessment/Plan:

62M hx HepC cirrhosis, newly decompensated with e/o decompensation (new-onset ascites) and hyponatremia.
# hyponatremia: Sodium 114, likely chronic, patient currently asymptomatic without concerning findings on neurological exam. Clinical findings suggestive of hypervolemic hyponatremia 2/2 decompensated cirrhosis resulting in decreased effective arterial blood volume and volume retention. However, the recent initiation of diuretics, mild AKI and early response to isotonic fluids in the ED suggests possible hypovolemic component.

  • 1L fluid restriction
  • q.4.h. sodium check, goal increase of 8mEq per 24h
  • hold diuretics

# hyperkalemia: Potassium 5.6, asymptomatic, AKI vs. medication-induced (aldactone). Continue monitoring.
# AKI: Elevated creatinine 1.1 from baseline 0.7. Likely pre-renal given recent initiation of diuretics. Consider hepatorenal syndrome given decompensated cirrhosis. Follow-up repeat creatinine after 1L NS bolus in ED.
# hepatitis C: decompensated with new-onset ascites. No e/o encephalopathy, continue home rifaximin.

Physiology of Hyponatremia: 1,2,3,4

Physiology of Hyponatremia

Differential Diagnosis of Hyponatremia: 5

Differential Diagnosis of Hyponatremia

Evaluation of Hyponatremia: 2

  1. Identification of onset (acute vs. chronic)
  2. Presence of symptoms (HA, nausea, confusion, seizures)
  3. Assessment of volume status (edema, JVD, skin turgor, postural BP)
  4. Medical history (cardiac, liver, renal disease), drug history

References:

  1. Freda BJ, Davidson MB, Hall PM. Evaluation of hyponatremia: a little physiology goes a long way. Cleve Clin J Med. 2004;71(8):639–650.
  2. Biswas M, Davies JS. Hyponatraemia in clinical practice. Postgrad Med J. 2007;83(980):373–378. doi:10.1136/pgmj.2006.056515.
  3. Adrogué HJ, Madias NE. Hyponatremia. N. Engl. J. Med. 2000;342(21):1581–1589. doi:10.1056/NEJM200005253422107.
  4. Marx JA, Hockberger RS, Walls RM, Adams JG. Rosen’s emergency medicine: concepts and clinical practice. 2010;1.
  5. Milionis HJ, Liamis GL, Elisaf MS. The hyponatremic patient: a systematic approach to laboratory diagnosis. CMAJ. 2002;166(8):1056–1062.