Angular: about HttpParams – Javascript

I have written a method in Angular, and I executed it by passing the argument q=’status’. However, the first console.log(params) did not include q=’status’, whereas the second console.log(params) included it. Why is that?

    getHospitalProfile(urlName: string, q: string | null = null): Observable<any> {
        let params = new HttpParams();
        if (q !== null) {
            params = params.set('q', q);
            console.log(params);
        }
        params = params.set('q', 'status');
        console.log(params);
        return this.http.get(`${this.apiUrl}/hospitals/${urlName}`, {
        ...this.httpOptions,
        observe: 'response',
        params: params
        })
        .pipe(
            map((res: HttpResponse<any>) => {
                if (res.status === 200) {
                    return res.body;
                }
            }),
            catchError(error => {
                throw error('ng');
            })
        );
    }