Hyponatremia refers to abnormally low sodium levels in the blood, often caused by excessive fluid intake, hormonal imbalances, or kidney problems.
| List I | List II |
|---|---|
| A. Heart | III. Atrial natriuretic factor |
| B. Kidney | I. Erythropoietin |
| C. Gastrointestinal Tract | IV. Secretnin |
| D. Adrenal Cortex | II. Aldosterone |


