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Difficulty: MediumMonitoring and Treatment Evaluation

A 52-year-old man is hospitalized for an acute manic episode characterized by severe psychomotor agitation, grandiose delusions, and a decreased need for sleep. He has a history of bipolar I disorder but has been nonadherent to medications for the past two years. After initial stabilization with an atypical antipsychotic, the decision is made to initiate lithium therapy for long-term mood stabilization. The patient has no other significant past medical history and takes no other medications. His vital signs and physical examination are within normal limits. Which of the following baseline investigations are indicated prior to starting this specific pharmacotherapy? (Select all that apply)

  1. Thyroid-stimulating hormoneAnswer
  2. Serum calcium and renal function panelAnswer
  3. ElectrocardiogramAnswer
  4. D
    Aspartate and alanine aminotransferases
  5. E
    Complete blood count with differential

Answer

The indicated baseline tests are thyroid-stimulating hormone, a serum calcium and renal function panel, and an electrocardiogram.
Lithium is a primary mood stabilizer with a narrow therapeutic index and specific organ toxicities. Baseline monitoring must evaluate for underlying conditions that lithium could exacerbate or that could affect its renal clearance. A renal function panel is mandatory because lithium is entirely renally excreted and can cause nephrogenic diabetes insipidus or chronic tubulointerstitial nephropathy. Baseline serum calcium is required because lithium can alter calcium homeostasis by causing hyperparathyroidism. Thyroid-stimulating hormone testing is necessary because lithium frequently causes hypothyroidism or goiter. Finally, an electrocardiogram is indicated for patients over the age of 40 (or those with pre-existing cardiac disease) because lithium can cause sinus node dysfunction, atrioventricular block, and repolarization changes.

Step-by-Step Solution

1
Identify the proposed treatment and its pharmacologic profile.
The patient is starting lithium for bipolar I disorder.
Different mood stabilizers have entirely distinct toxicity profiles and organ clearance mechanisms.
2
Recall the organ systems affected by lithium toxicity.
Lithium primarily affects the kidneys (nephropathy, diabetes insipidus), thyroid (hypothyroidism), parathyroid (hypercalcemia), and cardiac conduction system.
Identifying the target organs dictates which baseline laboratory and diagnostic tests are mandatory to establish a physiological baseline.
3
Select the appropriate tests based on the patient's specific demographics.
The patient requires evaluation of thyroid function, renal function, and serum calcium. Because he is over 40 years of age, an electrocardiogram is also indicated.
Age is a critical determining factor for baseline cardiac evaluation when starting this medication, as the risk for subclinical cardiac disease is higher.

Key Concept

Baseline physiological monitoring for lithium initiation includes evaluation of renal function, serum calcium, and thyroid function, as well as an electrocardiogram in patients over 40 years of age.
Estimated Time:1m 30s
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Topics

Monitoring and Treatment Evaluation

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