16 February 2021
: Case report 
An Unusual Case of Neurosyphilis Manifesting as Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
Unusual clinical course, Challenging differential diagnosis
Hannah L. Seay1BCDEF*, Loura Khallouf1BDEF, Alyson Lieberman1B, Sandeep S. Jubbal12BCDEGDOI: 10.12659/AJCR.929050
Am J Case Rep 2021; 22:e929050
Table 1. Laboratory values on admission.
| Laboratory values | Day 1 | Reference range |
|---|---|---|
| Hemoglobin (g/dL) | 13.1 | 13.2–17.1 |
| Hematocrit (%) | 38.5 | 39–52 |
| White blood cell count (10/uL) | 8.4 | 4.3–10.8 |
| Sodium (mmol/L) | 124 | 135–145 |
| Potassium (mmol/L) | 4.4 | 3.5–5.3 |
| Creatinine (mg/dL) | 0.81 | 0.60–1.30 |
| Blood urea nitrogen (mg/dL) | 10 | 7–23 |
| Rapid plasma reagin | Reactive | Non-reactive |
| Rapid plasma reagin titer | 1: 256 | |
| Fluorescent treponemal antibody absorption | Reactive | Non-reactive |
| Chlamydia trachomatis, RNA | Not detected | Not detected |
| Neisseria gonorrhoeae RNA | Not detected | Not detected |
| Serum osmolality (mOsm/kg) | 264 | 279–295 |
| HIV-1 RNA (copies/mL) | <20 Detected | Not detected |
| HIV-1 RNA PCR (Log copies/mL) | <1.30 Detected | Not detected |
| Absolute CD4 (cells/uL) | 188 | 370–1540 |
| Cortisol AM (ug/dL) | 12.9 | 6.7–22.6 |
| Specific gravity | 1.030 | 1.005–1.030 |
| Sodium (mmol/L) | 20 | |
| Creatinine (mg/dL) | 32 | 22–328 |
| Osmolality (mOsm/kg) | 148 | 70–900 |
| Glucose (mg/dL) | 68 | 50–80 |
| Protein (mg/dL) | 107 | 15–45 |
| Cryptococcal antigen | Not detected | Not detected |
| HSV 1 PCR | Not detected | Not detected |
| HSV 2 PCR | Not detected | Not detected |
| CSF culture | No growth | No growth |
| Venereal disease research laboratory test | Reactive 1: 4 | Non-reactive |
| CSF Gram stain | No organism seen | |
| HSV 1 DNA | Not detected | Not detected |
| HSV 2 DNA | Detected | Not detected |