What are the most likely laboratory findings in a 4-month-old boy with disseminated candidiasis, history of tetany, and truncus arteriosus?

From the Guidelines

The most likely laboratory findings in a 4-month-old boy with disseminated candidiasis, history of tetany, and truncus arteriosus would include low calcium levels, low parathyroid hormone (PTH), lymphopenia, and evidence of fungal infection, suggesting DiGeorge syndrome (22q11.2 deletion syndrome) as the underlying condition.

Key Laboratory Findings

• Low calcium levels (hypocalcemia) due to hypoparathyroidism, which is a component of DiGeorge syndrome 1
• Low parathyroid hormone (PTH) levels, further supporting hypoparathyroidism as a cause of the hypocalcemia
• Lymphopenia, indicating immunodeficiency, which is another key feature of DiGeorge syndrome
• Evidence of fungal infection, such as positive blood cultures for Candida species, elevated inflammatory markers (e.g., C-reactive protein, erythrocyte sedimentation rate), and possibly abnormal liver function tests due to the systemic nature of the infection
• Decreased T-cell counts and impaired T-cell function, consistent with thymic hypoplasia, a characteristic of DiGeorge syndrome
• Possible thrombocytopenia and anemia, which can occur in the context of disseminated infection and immunodeficiency

Diagnostic Considerations

Given the clinical presentation and laboratory findings, genetic testing to confirm the 22q11.2 deletion is essential. This diagnosis would explain the cardiac defect (truncus arteriosus), the history of tetany (due to hypocalcemia from hypoparathyroidism), and the predisposition to opportunistic infections like disseminated candidiasis (due to immunodeficiency from thymic hypoplasia) 1.

Management Implications

The management of this patient would involve antifungal therapy for the disseminated candidiasis, correction of the hypocalcemia, and consideration of immune system support or prophylaxis against future infections, depending on the severity of the immunodeficiency. The guidelines for managing candidiasis, including recommendations for antifungal therapy and the importance of removing central venous catheters, should be followed 1.

From the Research

Laboratory Findings

The most likely laboratory findings in a 4-month-old boy with disseminated candidiasis, history of tetany, and truncus arteriosus are:

• Low serum calcium concentration, as the patient has a history of tetany and was previously given vitamin D and calcium supplements 2, 3
• Elevated fungal titers, such as Candida species, in the blood or other bodily fluids, indicating disseminated candidiasis 4, 5
• Abnormalities in immune function tests, such as neutropenia or impaired lymphocyte function, which may contribute to the development of disseminated candidiasis 4, 6
• Possible elevation of inflammatory markers, such as procalcitonin or C-reactive protein, indicating a systemic inflammatory response to the infection 4

Antifungal Susceptibility

The antifungal susceptibility of the Candida species isolated from the patient may show:

• Sensitivity to amphotericin B, flucytosine, and other antifungal agents, such as posaconazole, caspofungin, and isavuconazole 2, 3, 5
• Variable susceptibility to azole antifungals, such as fluconazole, itraconazole, and voriconazole, with possible resistance or intermediate susceptibility 4, 6

Other Laboratory Findings

Other laboratory findings may include:

• Abnormalities in liver and kidney function tests, indicating possible organ dysfunction or damage due to the infection or underlying condition 4, 6
• Coagulation disorders, such as thrombocytopenia or prolonged prothrombin time, which may be associated with disseminated candidiasis or underlying hematological conditions 4, 5