diff --git a/src/entity/reference_range.ts b/src/entity/reference_range.ts
index 995d6e3..56e7929 100644
--- a/src/entity/reference_range.ts
+++ b/src/entity/reference_range.ts
@@ -16,30 +16,38 @@ export class ReferenceRange {
 	gender: Gender;
 
 	@Column({
+		type: 'integer',
 		nullable: false,
-		length: 128,
-		default: '0 day',
+		default: 0,
+		comment: 'Age range minimum in days',
 	})
-	age_range_min: string;
+	age_range_min: number;
 
 	@Column({
+		type: 'integer',
 		nullable: false,
-		length: 128,
-		default: '999 years',
+		default: 36500,
+		comment: 'Age range maximum in days (36500 = ~100 years)',
 	})
-	age_range_max: string;
+	age_range_max: number;
 
 	@Column({
+		type: 'decimal',
+		precision: 10,
+		scale: 2,
 		nullable: false,
-		length: 256,
+		comment: 'Minimum reference value',
 	})
-	value_min: string;
+	value_min: number;
 
 	@Column({
+		type: 'decimal',
+		precision: 10,
+		scale: 2,
 		nullable: false,
-		length: 256,
+		comment: 'Maximum reference value',
 	})
-	value_max: string;
+	value_max: number;
 
 	@Column({
 		nullable: false,