**Core Concept**
Preeclampsia is a pregnancy complication characterized by high blood pressure and often accompanied by significant amounts of protein in the urine. Laboratory tests are essential in diagnosing and managing preeclampsia. Platelet count is a critical parameter in assessing the severity of preeclampsia.

**Why the Correct Answer is Right**
A low platelet count (thrombocytopenia) is a common finding in preeclampsia, often occurring due to endothelial dysfunction and activation of the coagulation pathway. The low platelet count in this case (103,000/μL) is indicative of platelet consumption and activation, which is a hallmark of preeclampsia. This is because the placenta releases factors that activate platelets and the coagulation cascade, leading to thrombocytopenia.

**Why Each Wrong Option is Incorrect**
**Option B:** Creatinine 1.14 mg/dL is within the normal range for most individuals. Elevated creatinine levels may indicate kidney dysfunction, but it is not specific for preeclampsia.
**Option C:** Alkaline phosphatase 138 IU/L is also within the normal range. Alkaline phosphatase levels may be elevated in conditions such as pregnancy-induced liver enzyme elevation, but it is not a diagnostic criterion for preeclampsia.
**Option D:** Total protein of 258 mg in 24-hour urine is below the threshold for proteinuria, which is typically defined as 300 mg or more in a 24-hour urine collection. While proteinuria is a key feature of preeclampsia, this option does not support the diagnosis.

**Clinical Pearl / High-Yield Fact**
In preeclampsia, the platelet count often decreases as the disease severity increases. A platelet count below 100,000/μL is associated with a higher risk of complications and adverse outcomes.

**✓ Correct Answer: A. Platelet count 103,000 / μ L.**