CRP and familial primary hypomagnesemia: C-reactive protein (CRP) was categorized to <3, 3–10, 10–20 and >20 mg/L, sodium to <137 (hyponatremia), 137–145 and >145 mmol/L (hypernatremia), potassium to above or below 3.5 mmol/L (hypokalemia), and magnesium to above or below 0.7 mmol/L (hypomagnesemia), based on reference intervals at the laboratory of analysis, Clinical Chemistry at Lund University Hospital, Sweden.